Abstract:
A powered, gyroscopically balanced unicycle device to be used while standing, having leg contact surfaces which are made of a yielding, slightly soft material whose mild friction against the user&#39;s legs allows stable, precise control of the device without restraining the legs in any way. In one embodiment a single hubless wheel is driven by a friction drive mechanism which transmits torque from a motor through a drive wheel positioned below the foot platforms and in contact with the inner rim of the wheel. Various structures are provided for supporting the wheel and keeping it in place as it spins; absorbing small vertical movements of the wheel to prevent them from being transmitted to the foot platforms; enabling folding of the foot platforms; and facilitating carrying of the device by hand. Other embodiments are described and shown.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of provisional patent application Nos. 61/311,933 and 61/315,020 filed respectively on 2010 Mar. 9 and 2010 Mar. 18 by the present inventor. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to powered unicycles, and also to powered vehicles with gyroscopic self-balancing functionality. 
     BACKGROUND OF THE INVENTION 
     Examples in the prior art of electric-powered self-balancing vehicles for use while standing include those disclosed in U.S. Pat. No. 6,302,230 issued to Kamen et al. for Personal Mobility Vehicles and Methods (the &#39;230 patent), and U.S. patent application Ser. No. 12/281,101 by Simeray for Motorized Transport Vehicle for a Pedestrian (the &#39;101 application). 
     In a powered self-balancing unicycle, an electronic gyroscope that accelerates or decelerates the wheel in the appropriate direction is used to achieve fore-and-aft balance. This type of automatic fore-and-aft balance technology is taught in the &#39;230 patent. A sensor and the electronic gyroscope equipment are provided. Position 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. 
     The &#39;230 patent includes two-wheel and one-wheel embodiments, the two-wheel embodiment including the “Segway”, a highly-publicized personal transport device having a user platform between (or above) two parallel wheels. Among the one-wheel embodiments in the &#39;230 patent are some which, like the present invention, do not include a handle bar support by a shaft. However, since these do not provide any means for stabilizing the device with respect to the user&#39;s legs, they would require considerable skill to use, in addition to being difficult to control precisely. 
     It is greatly conducive to the comfort and safety of using the device if there is some means for stabilizing the device with respect to the user&#39;s legs, especially in situations where more precise control may be required, such as when mounting or dismounting, executing turns, passing over bumps in the riding surface, or keeping the device upright when ascending or descending a slope. Thus without specific considerations in the design of the vehicle for this purpose, this type of device would not be practical as a means of transportation. 
     The &#39;101 application teaches a single wheel, coupled to a frame to which two platforms (one on each side of the wheel) are attached. One of the defining features of the &#39;101 application is its “guide supports that tightly hold the user&#39;s legs”. These guide supports are shown as brackets in the form of bars or cuffs which hold the legs at knee or calf level and restrict the range of forward or backward leaning of the legs relative to the wheel, thereby providing greater stability for the user. Many embodiments of the &#39;101 application therefore generally meet the needs described above, since the user can press against the leg brackets for stability and for steering and tilting the device. However, the restraints imposed by the leg brackets introduce some inconvenience and, in some situations, danger in using the device, since when the user needs to dismount quickly the brackets may prevent him from doing so. There is therefore a need for an alternative means of achieving the same functions. 
     SUMMARY 
     The present inventor has discovered that all of the necessary functions performed by the leg brackets of the &#39;101 patent can be analogously performed by means of special surfaces provided on the device, which come into contact with only the proximal sides of the user&#39;s knees and/or lower legs. These leg contact surfaces are formed from a material chosen so as to supply a mild friction against the legs. The contact surfaces furthermore protrude slightly from the sides of the device, to the extent that they come into contact with the legs while the user is standing in a natural upright stance with his feet upon the foot platforms. These features are necessary in order to make the device easy and comfortable to operate without the inclusion of any kind of leg or foot restraints. The possibility of this arrangement appears to have been previously overlooked in the prior art. 
     This represents an approach to controlling a standing, powered, single-wheeled vehicle that differs from that of the &#39;101 application, in that the vehicle is controlled by gripping the device with the legs rather than by applying force to the front and back leg supports. Compared to embodiments of the &#39;101 application, the present invention has advantages in safety and convenience, and is incidentally also less complex to manufacture. With regards to other similar devices in the rest of the prior art (of which the single-wheeled handle-less embodiments of the &#39;230 patent are an example), the present invention is easier to use and offers more precise control. 
    
    
     
       DRAWINGS 
       Brief Description of Figures 
         FIG. 1  shows a side view of a powered unicycle device having a hubless wheel, friction drive system, and suspension system, with one side of its casing removed. 
         FIG. 2  shows the unicycle device of  FIG. 1  with entire casing present, leg contact surfaces, carrying handle, and two foldable foot platforms in unfolded position. 
         FIG. 3  shows the unicycle device of  FIG. 2  with the two foldable foot platforms in folded position. 
         FIG. 4  shows a front (or back) perspective view of another embodiment of a powered unicycle device having a single foot platform in transition between folded and unfolded position, with the entire casing removed. 
         FIG. 5  shows a perspective top profile view of the unicycle device of  FIGS. 1-3 , illustrating the slight concave curvature of the leg contact surfaces. 
         FIG. 6  shows a significantly different embodiment of a powered unicycle device with taller leg contact surfaces which are also adjustable. 
         FIG. 7  shows the unicycle device of  FIG. 6  with the leg contact surfaces slightly raised. 
         FIG. 8  shows another embodiment of a powered unicycle device having two foot platforms rigidly molded together with the casing. 
       
         
           
                 
               
                 
                 
               
             
                 
                     
                 
                 
                   DRAWINGS-List of Reference Numerals 
                 
                 
                     
                 
               
               
                 
                     
                 
               
            
             
                 
                   100 
                   Unicycle device (FIGS. 1-3, 5) 
                 
                 
                   110 
                   Wheel 
                 
                 
                   120 
                   Frame 
                 
                 
                   121 
                   Guide wheels 
                 
                 
                   122 
                   Guide wheel support members 
                 
                 
                   123 
                   Rib (on inner rim of wheel 110) 
                 
                 
                   130 
                   Motor 
                 
                 
                   131 
                   Drive wheel 
                 
                 
                   140 
                   Foot platforms-double 
                 
                 
                   141 
                   Cavity (for receiving foot platform) 
                 
                 
                   150 
                   Leg contact surfaces 
                 
                 
                   160 
                   Casing 
                 
                 
                   170 
                   Battery or batteries 
                 
                 
                   180 
                   Sliding component 
                 
                 
                   181 
                   Spring 
                 
                 
                   190 
                   Carrying handle 
                 
                 
                   200 
                   Unicycle device (FIG. 4) 
                 
                 
                   210 
                   Wheel 
                 
                 
                   240 
                   Foot platform-single 
                 
                 
                   300 
                   Unicycle device (FIGS. 6-7) 
                 
                 
                   350 
                   Leg contact surfaces-adjustable 
                 
                 
                   360 
                   Casing 
                 
                 
                   400 
                   Unicycle device (FIG. 8) 
                 
                 
                   440 
                   Foot platforms-one piece with casing 
                 
                 
                   460 
                   Casing 
                 
                 
                     
                 
               
            
           
         
       
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows one embodiment of a powered unicycle device  100 , with one side of the casing  160  removed. A single wheel  110  spins around a frame  120 . Frame  120  includes guide wheels  121  attached to the ends of respective guide wheel support members  122 . In this embodiment there are two pairs of guide wheels  121 , wherein the two guide wheels in each pair share the same axle and are positioned on opposite sides of their respective guide wheel support member  122 . A slightly extruded rib  123  is provided on the inner rim of wheel  110  and fits into the gap between the two guide wheels  121  in each pair. (Other arrangements, including those with more than one guide wheel support member, and those with only one guide wheel per support member, are possible.) Guide wheels  121  are therefore in contact with the inner rim of wheel  110  where they spin along with wheel  110  and hold wheel  110  in place by way of rib  123 . 
     On frame  120  is mounted a motor  130 , which directly drives a drive wheel  131  coupled to the frame  120  and positioned at the lowermost point along the inner rim of wheel  110 . Like guide wheels  121 , drive wheel  131  is in contact with the inner rim of wheel  110 . In this embodiment drive wheel  131  consists of a wide roller with a groove in the center into which rib  123  fits. By way of its contact with wheel  110 , drive wheel  131  transmits torque from motor  130  to wheel  110 . Since this drive system operates by friction, drive wheel  131  and the inner rim of wheel  110  must be pressed together with enough force to prevent slippage. With drive wheel  131  positioned directly beneath foot platforms  140 , the weight of the user provides the needed force. 
     One possible variation on the hubless drive system described above is one based on gear transmission instead of friction. The drive wheel is replaced by a gear, and accordingly the inner rim of the wheel has alternating protruding and indented segments (“teeth”). 
     A casing  160  encloses part or most of the device  100 . The two foot platforms  140  are coupled to casing  160 , with one on each side of wheel  110 . The user stands with one foot on each platform and faces toward the direction of travel of wheel  110 . A gyroscope system is associated with motor  130 ; it senses forward and backward tilt of frame  120  in relation to the ground and regulates the motor accordingly to keep frame  120  upright. This provides a means for controlling the acceleration and deceleration of the vehicle by leaning forward or backward, and also enables the vehicle to self-regulate its balance in the fore-and-aft plane. 
     In addition to being fixed to casing  160 , foot platforms  140  are also coupled to a sliding component  180 , which in this embodiment is formed as a hollow extruded rectangle capable of sliding along a substantially vertical path. A spring (or springs)  181  is attached to some part of frame  120  and to sliding component  180 . The two batteries  170  that supply power to motor  130  are rigidly affixed to casing  160 . (In this embodiment there are two batteries in order to create a balanced distribution of volume and weight, but there need not necessarily be two.) Casing  160 , foot platforms  140 , sliding component  180 , and batteries  170  can move vertically together as a unit, relative to frame  120 , wheel  110 , and all associated structures, while spring  181  biases the entire arrangement to a certain neutral position. In practice, the weight of the batteries and of the user cause the foot platforms, etc. to be less affected by bumps in the riding surface than the much lighter wheel and frame are, so that the wheel and frame lift over bumps while the structures supporting the user remain relatively stable. A space is provided in the top of casing  160  so that wheel  110  has room to lift upward. The overall effect is of a suspension or shock absorption system which increases comfort, ease of use, and safety for the user. This is significant for the viability of the device as a realistic means of transportation. 
       FIGS. 2 and 3  show the powered unicycle device  100  of  FIG. 1 , with the entire casing  160  present. Leg contact surfaces  150  protrude outward from the sides of casing  160  at a height where they may be in contact with the knees and/or upper calves of the user. The protrusion of leg contact surfaces  150  from the main body of casing  160  allows them to reach the user&#39;s legs when the user has her feet on foot platforms  140  and is standing in a natural upright position. Leg contact surfaces  150  are made of a yielding, slightly soft material, such as rubber. These features of leg contact surfaces  150  cause them to provide friction against the user&#39;s legs, thereby enabling the use of the user&#39;s legs to easily hold the device in place during use. This is important for stability, comfort, and ease of use, and is needed especially in situations where more precise control may be required, such as for instance when mounting or dismounting, executing turns, passing over bumps in the riding surface, and keeping the device upright when ascending or descending a slope. (It is also helpful for new users who are learning to use the device.) 
     Foot platforms  140 , coupled to casing  160 , are articulated so as to be upwardly foldable into a stowed position that narrows the profile of the device to aid in storage and carrying. A cavity  141  is provided on each side of casing  160  and is of suitable shape and depth for receiving foot platforms  140  in folded position. 
       FIGS. 2 and 3  also show a carrying handle  190  formed as part of casing  160 , above wheel  110 . Since this embodiment includes the suspension system described above, the handle may be cut into the abovementioned hollow space provided in the top of casing  160 . 
       FIG. 4  shows another embodiment of the present invention, with the casing removed. Unicycle device  200  is slightly different from unicycle device  100  of  FIGS. 1-3  in that there is a single foot platform  240 , which extends on both sides of wheel  210  and therefore acts the same as the double foot platforms  140  when in use. However, since foot platform  240  is a single rigid body, it folds for storage and carrying by tilting ninety degrees to one side (so that its profile is no wider than that of wheel  210 ). The other components of unicycle device  200  are arranged in a way that provides a gap which receives foot platform  240  in folded position. In this illustration foot platform  240  is shown in transition between folded and unfolded position. 
     The embodiment shown in  FIG. 5  may be either the embodiment of  FIGS. 1-3  or the embodiment of  FIG. 4 .  FIG. 5  shows that in this particular embodiment leg contact surfaces  150  bear a very slight concave curvature. This curvature approximately fits the user&#39;s knees or legs and can be an additional factor in providing a means by which the user may have easy, precise control of the device without resorting to any kind of leg restraint. 
       FIG. 6  shows another embodiment of a powered unicycle device  300  in accordance with the present invention. This embodiment is significantly different from unicycle devices  100  and  200  in that the wheel is not hubless, and accordingly is driven by a hub motor (a type of motor which is known in the art). This embodiment is also illustrative of another possible shape of leg contact surfaces  350 , which can keep contact with a large area of the user&#39;s lower leg; and a casing  360  which encloses a greater portion of the device than that of the embodiments shown in  FIGS. 1-5 . 
       FIG. 7  shows the unicycle device  300  of  FIG. 6 , wherein leg contact surfaces have been moved upward. The leg contact surfaces of this embodiment are configured so as to be capable of being raised and lowered in order to accommodate different possible heights and leg lengths of users. This adjustable leg contact surface is also applicable to many other embodiments besides this one. 
       FIG. 8  shows another embodiment of a powered unicycle device  400  having two foot platforms  440 , one rigidly affixed to each side of the wheel. Foot platforms  440  may be formed together with casing  460  from the same piece of material. Unicycle device  400  also has different implementation of leg contact surfaces  450  wherein they extend above the main body of the device. 
     Any embodiment of the present invention may further comprise means for detecting when the vehicle is turning—such as by detecting the sideways tilt which generally occurs during turning—and automatically adjusting the vehicle&#39;s speed and/or pitch (the angle of tilt in fore-and-aft dimension) to accommodate the turn. Without such means, small-radius turns may be difficult to execute, or may feel awkward or uncomfortable for the rider. For example, the rider may tend to bend his knees slightly during a turn, which can result in his lower legs angling forward. This may cause the vehicle to accelerate as an unwanted side effect. By tipping forward and/or decelerating slightly for the duration of the turn, the vehicle can compensate for the change in the rider&#39;s stance. 
     As shown in FIGS.  2  and  5 - 8 , the foot platforms  140 , 440  extend in a direction perpendicular to a central vertical plane of the wheel to a greater extent than the leg contact surfaces  150 , 350  extend in that direction. In  FIG. 5 , it can be seen that the foot platforms extend twice as much or more than the leg contact surfaces from the central vertical plane. 
     Although the description above contains many specificities, these should not be construed as limiting the scope of the embodiments but as merely providing illustrations of some of the presently preferred embodiments. Thus the scope of the embodiments should be determined by the appended claims and their legal equivalents, rather than by the examples given.