Abstract:
The disclosed method includes the steps positioning a first plurality of ball bearings around a spindle; enveloping the first plurality of ball bearings and the spindle with a bladder; and injecting a viscous substance into the bladder. The disclosed system includes a plurality of ball bearings; a bladder for enveloping the plurality of ball bearings; and an interface for connecting the bladder to a virtual reality means.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an input apparatus operating in a virtual reality environment. More specifically, the present invention is directed to a bladder driven omnidirectional moving surface used as an input device in a virtual reality system that simulates an exercising environment.  
           [0003]    2. Description of the Prior Art  
           [0004]    A major limitation in state-of-the-art virtual reality systems is the inability to permit simple walking and running. In such systems, navigation is typically experienced as a disembodied center of consciousness which is directed by pointing, or by manipulation of a joystick, trackball, mouse, or similar device. The actual physical sensation of walking is limited to one of two forms: a) The user is restricted to a confined and immobile surface where tracking and signal generation are well-controlled, and b) the user is confined to a device such as a linear treadmill or wheelchair which transduces the user&#39;s linear motion to virtual space navigation.  
           [0005]    The conventional linear treadmill has a movable track which can be upwardly inclined. The track is only movable in one direction, which restricts motion of the user to the direction of movement of the track. A monitor, such as a motivational electric display, associated with the track typically records the time, speed, and distance accomplished by the user.  
           [0006]    Use of a linear treadmill, consisting of one continuous moving track, in conjunction with a monitor permits a user to walk in a straight line. Users cannot step in arbitrary directions as they would be able to in real life. This limitation in directionality detracts from the immersive nature of the experience, and requires that the experience take on more of a vehicular nature rather than freely walking and navigating body.  
           [0007]    U.S. Pat. No. 5,562,572 discloses an omni-directional treadmill that would eliminate the aforementioned directionality limitation. Because that system is based on two sets of conveyors, one enabling movement in a direction perpendicular to the other, that system may not function as expected when users decide to take turns that are diagonal to the rotation of the conveyors. Consequently, there is a need in the art for a fully omni-directional moving surface that can be used as a treadmill.  
         SUMMARY OF THE INVENTION  
         [0008]    The systems and methods of the present invention combine the use of a novel moving surface assembly with virtual reality systems.  
           [0009]    More specifically, the method includes the steps of positioning a first plurality of ball bearings around a spindle; enveloping the first plurality of ball bearings and the spindle with a bladder; and injecting a viscous substance into the bladder. The method further includes the steps of positioning a second plurality of ball bearings in a base; placing the bladder in the base such that the bladder is in contact with the second plurality of ball bearings; positioning a trackball in between the base and the bladder; and connecting the trackball to a processor used for providing a virtual reality environment.  
           [0010]    The system of the present invention includes a plurality of ball bearings; a bladder for enveloping the plurality of ball bearings; and an interface for connecting the bladder to a virtual reality processor. The system further includes a spindle for positioning the ball bearings such that the ball bearings form a ring around the spindle, the spindle having a top portion to support the weight of a user; a base including a plurality of ball bearings for holding the bladder; a viscous substance enveloped by the bladder and in contact with the ball bearings; and a track ball contacting the bladder and serving as an interface between the bladder and the virtual reality processor.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The preferred embodiments of this invention will be described in detail, with reference to the following figures, wherein:  
         [0012]    [0012]FIG. 1 is a diagram showing a side view of the spindle used as an omnidirectional walking surface in the treadmill of the present invention;  
         [0013]    [0013]FIG. 2 is a diagram showing a top view of the spindle;  
         [0014]    [0014]FIG. 3 is a diagram showing ball bearings forming a ring around the spindle;  
         [0015]    FIGS.  4 A-B are diagrams showing processes of enveloping the bladder around the spindle;  
         [0016]    FIGS.  5 A-D are diagrams showing the bladder enveloping the ball bearing encircled spindle;  
         [0017]    FIGS.  6 A-C are diagrams showing an omni-directional base;  
         [0018]    [0018]FIG. 7 is a diagram showing a side view of the bladder and the spindle inserted in the omni-directional base; and  
         [0019]    [0019]FIG. 8 is a diagram illustrating the use of the omni-directional treadmill.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]    The present invention includes a bladder driven omnidirectional moving surface that may be used as a treadmill designed to enable full 360-degree freedom of locomotion. Users may walk, jog or run on the omnidirectional treadmill in any direction, at any velocity, and they may also safely and naturally change direction while in motion.  
         [0021]    By enabling full 360-degree freedom of locomotion, the omnidirectional treadmill offers a new alternative to conventional mono-directional treadmill use. The mechanics of the omnidirectional treadmill allow the use of mouse-trackball technology to track the user&#39;s locomotion gestures in any direction, and at any rate. With this, the omnidirectional treadmill may be used alone, or in conjunction with a computer generated 360-degree interactive virtual reality environment. This virtual environment responds, in real-time, to the participant&#39;s foot movement on the omnidirectional treadmill. The electronic virtual reality environment may be delivered to the participant via virtual reality glasses or on a surrounding projection screen with audio support.  
         [0022]    There are basically five components which are strategically assembled in order to create a functional omnidirectional moving surface: a spindle or walking platform; a series of ball-bearings; a bladder; an omnidirectional base or platform; and a trackball sensor.  
         [0023]    Spindle-Walking Platform  
         [0024]    [0024]FIG. 1 illustrates a side view of the spindle  101 . The spindle  101  may be approximately eight to ten inches high, five-feet in diameter and may weigh from thirty to forty pounds. The spindle  101  may be made of a very robust, yet very lightweight polymer-plastic or nylon material, and should be symmetrical in all dimensions, i.e., top-side-front (see, for example, FIG. 2 for a top view).  
         [0025]    The top (locomotion) surface  103  of the spindle  101  is convex. This particular design-dynamic promotes a focused center-of-gravity. The convex nature of the walking/running surface brings the user back to the center of the pad via gravity. The top surface  103  may have a low coefficient of friction.  
         [0026]    Ball Bearings  
         [0027]    [0027]FIG. 3 illustrates a number of ball-bearings  301  forming a ring around the spindle  101 . There maybe approximately 10 to 15 lightweight, hollow, hard-plastic ball bearings forming a complete ring around the spindle  101  partially within the spindle groove  105 . Each ball bearing may be approximately eight inches in diameter and may weight three to four ounces.  
         [0028]    The exact (finite) diameter of the ball bearings may be defined by the size of the outer groove  105  of the spindle  101 . The ball bearings  301  enable the free 360-degree mobility of the bladder  401  (see FIG. 4).  
         [0029]    Bladder  
         [0030]    [0030]FIG. 4A illustrates a first embodiment for enveloping the spindle  101  and the spindle-bearings  301  with the bladder  401 . The bladder  401  may be manufactured as a five-foot spherical rubber-polymer.  
         [0031]    In a first embodiment, the bladder  401  is an exceptionally strong and exceptionally pliable spherical hollow rubber-polymer balloon which completely and seamlessly envelops the entire spindle-ball bearing unit. The bladder  401  is first slit open, for example, into two equal hemispheres as illustrated in step  411 . The spindle  101  and the ball bearings  301  are then introduced into the bladder  401 , as shown in step  412 . Finally, the bladder  401  envelops the spindle  101  and ball bearings  301 . Heat may then be used to seal the bladder  401 , forming a seamless rubber polymer bladder that revolves in 360 degrees around its inner support (i.e., the combination of spindle  101  and ball bearings  301 ). Step  413  illustrates the heat sealing process.  
         [0032]    After the bladder  401  has been heat sealed, a viscous substance, such as a silicon fluid, is hypodermically injected through the bladder skin onto the spindle  101  and ball bearings  301 . This provides lubrication of the ball bearings  301 , which facilitates the rotation of the ball bearings and of the movement of the bladder  401 . Alternatively, the viscous substance may be periodically added or removed from the sealed bladder  401  through a valve component. The valve component may be similar to the valve component of a basketball.  
         [0033]    In a second embodiment, the bladder  401  may be manufactured as a highly elastic spheroid with a 4 to 6 inch hole  431  in it, as shown in step  421 . The elastic nature of the bladder  401  allows the hole  431  to expand as shown in step  422 . The spindle  101  and the ball bearings  301  are then inserted through the hole  431  into the bladder  401  as shown in step  423 . The hole  431  would thereafter acquire a smaller shape as illustrated in step  424 .  
         [0034]    The bladder hole  431  may then be covered with a patch of the same bladder material. The patch may be affixed with a heat sealing process, such as the process used in the first embodiment.  
         [0035]    The second embodiment of bladder envelopment may also include incorporating a passage way (e.g., similar to a basketball inflation system) where the viscous substance may be added or subtracted to or from the bladder  401 . The viscous substance may also be injected into the bladder  401  as described above. Adjusting the amount of viscous substance inside the bladder  401  allows a user to tighten or loosen the bladder  401  around its inner frame. Users may then customize the feel of the omni-directional moving surface to their own liking.  
         [0036]    The bladder may be fabricated of a highly flexible and yet, extremely durable (approximately ¼″ thick) rubber-like polymer which can be walked or run upon at any speed by a person of any size and weight. The bladder material is flexible enough to enable a 360-degree change in walking or running direction without crimping, dragging, or hampering the user&#39;s locomotion in any way. Polymers with such properties have been developed and they are currently being improved upon by many plastics manufacturers around the world.  
         [0037]    An example of such polymers is “moneprene” which is a thermoplastic elastometer; meaning that it has the ability to be sealed with heat.  
         [0038]    Gum rubber is another example of the material having the desired properties. It may be first formed as a sheet shaped into a continuous spherical shell, resembling a round, un-inflated balloon. The sheet may be spherical in order to provide isotropic properties with respect to movement of the bladder in any direction over the inner frame.  
         [0039]    In either embodiment, the bladder  401  is fitted around the spindle-ball bearing unit tightly enough so that it does not crimp or fold, but loose enough so that it moves or revolves freely around the spindle-ball bearing unit so as to readily enable omnidirectional locomotion. The bladder  401  is the actual moving surface that makes contact with the user&#39;s feet and is the element that enables 360-degree mobility and can change direction at any rate or revolution with little or no resistance. Further, it physically relays the users foot-input information to an underlying trackball  801  (see FIG. 7).  
         [0040]    The trackball  801  relays the exact position, direction and velocity coordinates of the user to a processor (not shown) that then directs a displayed 3D environment to move in direct, real-time correspondence with the users walking and/or running gestures. This provides an illusion for the user of “moving through-and-about” a virtual reality environment.  
         [0041]    In summary, the bladder  401  easily moves or rolls around the spindle-ball bearing unit in a 360 degree treadmill fashion. The spherical and elastic nature of the bladder enables its revolution in every direction (gyration) around the spindle/ball bearing unit.  
         [0042]    Viscous Fluid Injection  
         [0043]    As discussed above, once the bladder  401  is properly manufactured around the spindle-ball bearing unit, a highly viscous substance  501  (see FIG. 5A) may be injected through the skin of the bladder  401  onto the ring of ball bearings  301  which encircle the spindle  101 . The viscous substance  501  may be, for example, thick oil or liquid silicon. This process further ensures the ease of mobility and overall responsiveness of the bladder&#39;s movement around its frame. Further, it enhances the “natural feel” of walking or running on the 360-degree treadmill of the present invention.  
         [0044]    The single unit formed by the conglomeration of the spindle  101 , ball bearings  301 , and the bladder  401  as described above is hereinafter referred to as the bobbin  605 . When assembled, the bobbin  605  may resemble a five-foot diameter, eight-inch high blood cell or pancake.  
         [0045]    [0045]FIG. 5B shows a view of the bladder  401  stretched around the spindle assembly (i.e., the bobbin  605 ). FIG. 5C illustrates a side view of the bobbin  605 . FIG. 5D illustrates a top view of the bobbin  605 . In the bobbin, the spindle-ball bearing components are completely enveloped by the bladder  401  and immersed in viscous fluid  501 .  
         [0046]    OmniDirectional Base  
         [0047]    [0047]FIG. 6A shows the omnidirectional base  601 . The bobbin  605 , having no stationary surfaces, may be “nested” into a floor standing base (the base  601 ) which allows the bladder  401  full freedom of 360-degree mobility while keeping the entire bobbin  605  securely and safely in place.  
         [0048]    The omnidirectional base  601  may be a circular, one foot high, six foot diameter lightweight platform which cups the bobbin  605 . Platform  601  preferably has a double ring of ball bearings around its inner circumference, comprised of an outer ring of hollow plastic ball bearings  603  and a second lower ring of ball bearings  703  may be placed around the inner circumference of the base  601 . The double ring formed by the ball bearings  703  and  603  are supporting surfaces which lie in direct contact with the revolving bladder  401 . See FIG. 7.  
         [0049]    The ball bearings  703  and  603  may be hollow and manufactured of a lightweight (hard-plastic) polymer. Further, they may be made of the same material as the ball bearings  301  that are inside the bobbin  605 .  
         [0050]    The ball bearings  703  enable full freedom of 360-degree movement for the bladder  401  while simultaneously acting as the main support of the entire bobbin  605 . The omnidirectional base  601  may sit directly on the floor. FIGS. 6B and 6C illustrate a side view and a top view of the base  601  respectively.  
         [0051]    Trackball  
         [0052]    Mounted in the center-bottom of the omnidirectional base  601  is a trackball sensor  801 . This component may be similar to that used in a standard computer mouse. For example, the trackball  801  may have a four-inch diameter, and may be made of the same material as the standard computer mouse trackball. The trackball  801  may be mounted in its own base  803  which sits on the floor in the center of the omnidirectional base  601  (see FIG. 7). Sitting in its own base-mount, the trackball  801  may merely touch the rotating center underside of the bladder  401 . The motion of the bladder  401  motivates (or rolls) the trackball  801 .  
         [0053]    The trackball  801  may lie in direct contact with the bladder  401  but does not hinder its mobility whatsoever. The trackball  801  merely records the motion information of the revolving bladder  401  and then transmits that information to the processor (not shown). The processor translates physical motion-information generated by trackball  801  into meaningful data indicative of the user&#39;s position, direction and velocity within the electronic virtual environment.  
         [0054]    Turning to FIG. 8., the disclosed omni-directional moving surface enables users to walk, run or jog in any direction, at any rate, and gives them the ability to change direction while engaged in locomotion. The user is expected to plug a cable  801  connecting the trackball to the computer&#39;s USB or serial port  803 ; step on to the moving surface, put on virtual reality glasses  805 , and proceed to maneuver through-and-about 360 degree virtual reality exercise environments.  
         [0055]    The interaction that occurs between the user and the moving surface is relatively simple and exactly similar to a user&#39;s interaction with a conventional mono-directional treadmill (except that locomotion is capable in all directions). The process is: put on sneakers and virtual reality glasses, get on omni-directional treadmill, and walk, run and/or jog in any direction as you would in every day life. The moving surface should become “invisible” to the user, requiring the user to use no more effort in omni-directional locomotion as in conventional (real-world) omni-directional locomotion.  
         [0056]    An encircling guard rail  807  surrounding the user at arms distance may be used, such that users do not fall off the treadmill or lose their balance.  
         [0057]    While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations are apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative and not limiting. Various changes may be made without departing from the spirit and scope of the invention.