Abstract:
A self-balancing powered unicycle device ( 100 ) having a single hubless wheel is disclosed. The self-balancing powered unicycle device comprises: a single wheel ( 120 ); a motor adapted to drive the wheel; a balance control system adapted to maintain fore-aft balance of the unicycle device; at least one foot platform ( 165 ) for supporting a user of the unicycle device; and a casing ( 110 ) adapted to cover at least a portion of the outer rim of the wheel. The self-balancing powered unicycle device further comprises at least one energy storage device compartment ( 150 A,  150 B) protruding outward from a side of the casing ( 110 ) and adapted to house an energy storage device for powering the unicycle device.

Description:
FIELD OF INVENTION 
       [0001]    The present invention relates to powered single-wheeled devices and more particularly to powered unicycles with self-balancing functionality. 
       BACKGROUND TO THE INVENTION 
       [0002]    Powered self-balancing vehicles for use while standing are known. Such vehicles include two-wheeled vehicles and single-wheeled vehicles (i.e. unicycles). 
         [0003]    In a powered self-balancing unicycle, an electronic or mechanical system that controls the wheel in the appropriate direction is typically used to achieve fore-and-aft balance. This type of automatic fore-and-aft balance technology is well known and described, for example, in U.S. Pat. No. 6,302,230. A sensor and electronic equipment are typically provided. Information detected by the sensor and the electronics is relayed to a motor. The motor drives the wheel in the appropriate direction and at sufficient speed to maintain fore-and-aft balance. 
         [0004]    Known embodiments of a powered self-balancing unicycle do not include a handle bar supported by a shaft. For example, U.S. patent application Ser. No. 12/281,101 presents a single wheel, coupled to a frame to which two platforms (one on each side of the wheel) are attached. 
       SUMMARY OF THE INVENTION 
       [0005]    According to a first aspect of the invention, there is provided a self-balancing powered unicycle device, comprising: a single wheel; a motor adapted to drive the wheel; a balance control system adapted to maintain fore-aft balance of the unicycle device; at least one foot platform for supporting a user of the unicycle device; a casing adapted to cover at least a portion of the outer rim of the wheel; and at least one energy storage device compartment protruding outward from a side of the casing and adapted to house an energy storage device for powering the unicycle device. 
         [0006]    For the avoidance of doubt, reference to a single wheel should be taken to mean the generally circular unit that is positioned between the legs of a user and adapted to rotate about an axis to propel the unicycle in a direction during use. The single wheel may therefore be formed from one or more tyres and/or hubs that are coupled together (via a differential, for example). For example, an embodiment may comprise a single hubless wheel having a single hubless rim with a plurality of separate tyres fitted thereon. Alternatively, an embodiment may comprise a single hubless wheel formed from a plurality of hubless rims (each having a respective tyre fitted thereon), wherein the plurality of hubless rims are coupled together via a differential bearing arrangement. A yet further embodiment may comprise a single wheel having a single rim and hub with a plurality of separate tyres fitted thereon. An even yet further embodiment may comprise a single wheel formed from a plurality of hubs and rims (each having a respective tyre fitted thereon), wherein the plurality of hub and rims are coupled together via a differential bearing arrangement. 
         [0007]    There is proposed a self-balancing powered unicycle comprising a casing which may enable the powering device (such as a battery, for example) to be positioned outside of the rotating wheel, thereby enabling the wheel and/or the powered unicycle to be made slimmer than conventional self-balancing powered unicycles. 
         [0008]    In other words, by catering for placement of an energy storage device outside the plane of the single wheel, the lateral extent of the wheel may be minimised. Also, the energy storage device compartment of the casing may provide a larger space for accommodating a larger energy storage device than conventional self-balancing powered unicycles. Embodiments may therefore employ a larger, more powerful energy storage device without needing to increase in the width of the wheel. 
         [0009]    By housing an energy storage device in a compartment or storage part/section of the casing, the energy storage device may be protected from damage, water and/or dust despite being positioned exterior to the single rotating wheel. 
         [0010]    The at least one energy storage device compartment may be adapted to be removable from the casing so as to enable removal of an energy storage device from the unicycle device. Embodiments may thus provide an energy storage arrangement which can be quickly and easily connected or removed to/from the unicycle for repair or replacement, for example. Also, by being adapted to be removable from the casing, embodiments may be dismantled to reduce the overall size or profile of the unicycle, thereby improving portability. 
         [0011]    Embodiments may provide a self-balancing powered unicycle that is modular in nature. The at least one energy storage device compartment may be easily engaged and disengaged to/from the wheel to facilitate rapid and simple repair or replacement. 
         [0012]    The energy storage device compartment may be shaped such that its width increases with distance from the rotational axis of the single wheel. Such a shape may help to reduce, minimise or prevent contact of a user&#39;s legs (e.g. knees and/or calves) with the casing and/or protruding compartment during general use. In particular, it is noted that when manoeuvring (e.g. turning) a powered unicycle device (such as an embodiment of the invention), the user will typically move and/or tilt their legs fore or aft. The sharper or greater the turn the more the legs may move or tilt. By arranging the shape of the protruding energy storage device compartment to increase in width or size with distance from the rotational axis of the single wheel, the size of the protruding energy storage device compartment can be maximised whilst reducing, minimising or preventing its contact with user&#39;s legs during use. In other words, the shape and lateral extent of a protruding energy storage device compartment may be adapted to avoid or reduce contact with a user&#39;s leg during use, yet still be of maximum size so as to house a large energy storage device. Embodiments may also enable sharper turns to be made by a user. When a user manoeuvres the unicycle device, the user may tilt or move their leg(s) fore/aft ahead/behind the energy storage device compartment, whilst the energy storage device compartment is shaped so that the separation between the leg and compartment is reduced towards a minimum (to maximise the size of the compartment). The increase in width of the energy storage device compartment with distance from the rotational axis of the single wheel may not be linear, and so, in some embodiments, the energy storage device compartment may have curved sides or edges when viewed from a side of the unicycle device. 
         [0013]    In an embodiment, the at least one energy storage device compartment may be V-shaped, with the vertex or narrower end of the V-shape pointing towards the rotational axis of the single wheel. In other embodiments, the at least one energy storage device compartment may be trapezoidal in shape (e.g. a trapezium) or kite-shaped. 
         [0014]    Also, in some embodiments, the at least one energy storage device compartment may extend beyond the circumferential extent of the generally circular casing, thus meaning that the size of the at least one energy storage device compartment is not generally restricted by the circumference of the wheel or casing. 
         [0015]    In other embodiments, however, the at least one energy storage device compartment may not extend beyond the circumferential extent of the generally circular casing so as to reduce the overall size the unicycle. In such embodiments, the size of the at least one energy storage device compartment may be generally restricted by the circumference of the wheel or casing. 
         [0016]    An outwardly facing surface of the at least one energy storage device compartment may comprise a yielding material. Such yielding material may be chosen so as to provide friction with a ground surface and thereby restrict or reduce a sliding movement of the unicycle device across the ground (if a user falls from the unicycle for example). An exemplary yielding material may comprise a rubberised or polymer-based material for example. 
         [0017]    An outwardly facing surface of the at least one energy storage device compartment may therefore perform multiple functions, including the protection of a housed battery, and/or the provision of grip between the side of the unicycle device and the ground/floor surface (to prevent the unicycle from sliding along the ground/floor in an accident for example). The at least one energy storage device compartment may thus provide for improved safety and protection of an energy storage device housed therein. 
         [0018]    The energy storage device may comprise at least one of: an electrical battery; an electrochemical battery, a capacitor, and a mechanical energy storage device; and a capacitor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    An example of the invention will now be described with reference to the accompanying diagrams, in which: 
           [0020]      FIG. 1  is an isometric view of an embodiment of a powered unicycle device; 
           [0021]      FIG. 2  is an exploded diagram of the powered unicycle device of  FIG. 1 , 
           [0022]      FIGS. 3A &amp; 3B  are side and front elevations, respectively, of the embodiment of  FIG. 1 ; and 
           [0023]      FIG. 4  is an isometric view of an alternative embodiment, wherein the battery compartments are detached from the powered unicycle device. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]      FIGS. 1-3  show one embodiment of a powered unicycle device  100 .  FIG. 1  shows the powered unicycle device  100  with a casing  110  which covers a significant portion (e.g. more than half) of the wheel  120 . Here, the casing  110  is formed from a first, left portion  110 A that covers a significant portion of the left half of the wheel  120 , and a second, right portion  110 B that covers the a significant portion of the right half of the wheel  120 .  FIG. 2  illustrates internal components of the unicycle device  100 , namely a wheel  120  (which spins about a central axis  125 ) and drive arrangement  135 . 
         [0025]    Referring back to  FIG. 1 , the casing  110  is retained in a fixed position relative to the central axis  125 . 
         [0026]    Referring now to  FIG. 2 , rotation of the single wheel  120  is driven by a drive arrangement  135  according to an embodiment. The drive arrangement  135  includes pairs of guide wheels (not visible) attached to the rim of the drive arrangement  135 . A rib (not visible) is provided around the inner rim of the wheel  120  and fits into a gap between the guide wheels of each pair. The guide wheels are therefore adapted to contact with the inner rim of wheel  120  where they spin along with wheel  120  and hold wheel  120  in place by way of the rib  150 . Of course, it will be appreciated that other arrangements, including those with only one guide wheel, are possible. 
         [0027]    For powering the drive arrangement  135 , first  145 A and second  145 B batteries are provided in first  150 A and second  150 B battery compartments of the casing, respectively. 
         [0028]    When fitted to the casing  110 , as depicted in  FIG. 1 ), the battery compartments  150 A,  150 B protrude outwardly from the side of the casing  110  and adapted to house a battery for powering the unicycle device. Thus, the casing  110  is adapted to enable the batteries  145 A, 145 B to be positioned outside of the rotating wheel (and thus external to the drive arrangement  135 ), thereby enabling the wheel to be slimmer. In other words, by catering for placement of a batteries  145 A, 145 B outside the plane of the single wheel  120 , the lateral extent of the wheel may be minimized. Also, the battery compartments  150 A, 150 B may be adapted to provide a larger space for accommodating bigger batteries than conventional self-balancing powered unicycles. The depicted embodiment may therefore employ larger, more powerful batteries than conventional self-balancing powered unicycles whilst maintaining or reducing the width of the wheel. 
         [0029]    The first  150 A and second  150 B battery compartments house first  145 A and second  145 B batteries, respectively. The battery compartments thus protect the batteries from damage, water and/or dust. 
         [0030]    The batteries  145 A, 145 B are adapted to power a motor (of the drive arrangement) which drives one or more drive wheels (not visible) positioned at the lowermost point along the inner rim of the wheel  120 . The batteries  145 A, 145 B are adapted to electrically connect to a metal framework  160  which is adapted to conduct electrical energy to supply power to a motor of the unicycle device  100 . In this embodiment, there are two batteries in order to create a balanced distribution of volume and weight. However, it is not necessary to employ two batteries  145 A, 145 B. Also, alternative energy storage arrangements may be used, such as capacitors, and other known power storage devices, for example. 
         [0031]    In this example, the first  150 A and second  150 B battery compartments are shaped such their width (when viewed from the side of the unicycle device, as in  FIG. 3A ) increases with distance from the rotational axis  125  of the single wheel  120 . In other words, the battery compartments  150 A,  150 B are trapezoidal or generally V-shaped, with the narrow end pointing towards the rotational axis  125  of the single wheel  120 . This shaping of the battery compartments is designed to reduce, minimize or prevent contact of a user&#39;s legs (e.g. knees and/or calves) with the casing  110  and/or protruding compartments  150 A, 150 B during general use of the unicycle device  100 . 
         [0032]    In particular, it is noted that when turning a powered unicycle device (such as an embodiment of the invention), the user will typically tilt or move their legs forwards or backwards. The sharper or greater the turn, the more the legs may tilt or move forwards or backwards. By arranging the shape of the protruding battery compartments  150 A, 150 B be of larger width or size towards an end furthest away from the rotational axis  125  of the wheel  120 , the size of the protruding battery compartment may be maximized whilst reducing, minimizing or preventing its contact with user&#39;s legs during use. In other words, the shape and lateral extent of a protruding battery compartment  105 A, 150 B is adapted to avoid or reduce contact with a user&#39;s leg during use, yet still be of maximum size so as to house a large battery  145 A, 145 B. 
         [0033]    When a user manoeuvres the unicycle device  100 , the user may tilt or move their legs forwards or backwards ahead or behind the battery compartment, whilst the battery compartments  150 A, 150 B are shaped so that the separation between the user&#39;s leg and a battery compartment  150 A, 150 B is reduced towards a minimum (so as to maximize its size). 
         [0034]    The outwardly facing surface of each battery compartment  150 A, 150 B is provided with a yielding material  155  thereon. The yielding material  155  is of this example is chosen so as to provide friction with a ground surface and thereby restrict or reduce a sliding movement of the unicycle device across the ground (if a user falls from the unicycle for example). Here, yielding material  155  comprises a rubberised or polymer-based material. 
         [0035]    The outwardly facing surface of each battery compartment  150 A, 150 B therefore perform multiple functions, including the protection of a battery housed therein, and the provision of grip between the side of the unicycle device  100  and the ground/floor surface (to prevent the unicycle from sliding along the ground/floor in an accident for example). 
         [0036]    The wheel  120  is hubless and the drive arrangement  135  is adapted to be fitted inside the wheel. In other words, the drive arrangement is sized and shaped so that it can be positioned in the void define by the inner rim of the hubless wheel  120 . 
         [0037]    Two foot platforms  165  are coupled to the axle  125  of the wheel, wherein a platform  165  is situated on either side of wheel  120 . The foot platforms  165  are movable between a stowed configuration, wherein the foot platforms are substantially parallel with the plane of the wheel (as shown in  FIGS. 1 &amp; 3 ), and an active configuration, wherein the foot platforms are substantially perpendicular to the plane of the wheel (as shown in  FIG. 2 ) so as to support a user&#39;s weight. Thus, in this embodiment, the foot platforms  165  are movable between: (i) a stowed configuration wherein they are flat against the side of the wheel; and (ii) an active configuration, wherein they project outwardly from the side of the wheel to provide a support surface for the feet of a user. Accordingly, the foot platforms  165  are upwardly foldable into a stowed configuration that narrows the profile of the unicycle  100  to aid in storage and carrying. In use, the foot platforms are moved to the active configuration, and the user stands with one foot on each platform  165 . 
         [0038]    The foot platforms  165  are formed with removed portions (or voids)  170  for reduced weight. 
         [0039]    The drive arrangement  135  includes a gyroscope or accelerometer system (not shown) which senses forward and backward tilt of the device in relation to the ground surface and regulates the motor accordingly to keep the device upright. In this way, the user is provided a way of controlling the acceleration and deceleration of the unicycle by varying the pressure applied to various areas of the foot platforms  165 . It also enables the unicycle to self-regulate its balance in the fore-and-aft plane. 
         [0040]    The casing  110  of the embodiment of  FIGS. 1-3  also comprises a lifting handle  180 . The lifting handle  180  is positioned at the top of the casing  110 , above the wheel  120 , and may be used to hold the unicycle  100  above the ground, for example to enable a user to lift, carry, convey or place the unicycle  100 . 
         [0041]    Turning now for  FIG. 4 , there is depicted another embodiment (which is slightly modified when compared to the embodiment of  FIGS. 1-3 ), wherein the battery compartments  150 A, 150 B are adapted to be removable from the casing  110 . In  FIG. 4 , the battery compartments  150 A, 150 B are shown to be detached from the unicycle device  100 , and the arrows illustrate how the battery compartments  150 A, 150 B can be attached/detached to/from the casing  110  of the unicycle device  100 . It is also noted that the battery compartments  150 A, 150 B of this embodiment are flatter than those of  FIGS. 1-3  since they do not comprise a projected section which is adapted to extend over the top the casing  110 . 
         [0042]    It will be understood that removal of the battery compartments  150 A, 150 B, enables removal of the batteries  145 A, 145 B housed within the battery compartments  150 A, 150 B. The depicted embodiment thus provides a battery arrangement which can be quickly and easily connected/removed to/from the unicycle device  100  for repair or replacement, for example. Also, by being adapted to be removable from the casing  110 , the depicted embodiment may be dismantled to reduce the overall size or profile of the unicycle, thereby improving its portability. The embodiment of  FIG. 4  may therefore be considered as being modular in nature. 
         [0043]    It is also noted that the foot platforms  165  of this embodiment are different from those of  FIGS. 1-3  in that they do not comprise removed portions (or voids). 
         [0044]    While specific embodiments have been described herein for purposes of illustration, various modifications will be apparent to a person skilled in the art and may be made without departing from the scope of the invention. 
         [0045]    It will be appreciated that a variation on the hubless drive arrangement described above may be based on gear transmission instead of friction. The drive wheels may thus be replaced by circular gears for example, and accordingly the inner rim of the hubless wheel may have alternating protruding and indented segments (i.e. “teeth”). Other embodiments may not employ a hubless wheel, but may instead employ a ‘hubbed’ wheel. 
         [0046]    A retractable carrying strap may also be provided and attached to the top of the casing, for example. Such a carrying strap may be used to carry the unicycle, for example over the shoulder of user. A hook may be provided on the bottom of the case to create rucksack-like belts from the carrying strap. 
         [0047]    Further, in some embodiments, the battery compartment(s) may extend beyond the circumferential extent of the generally circular casing, thus meaning that the size of the battery compartment(s) may not be generally restricted by the circumference of the wheel or casing.