Abstract:
A treadmill having a belt assembly allows a user the walk or run in any direction. A single helically wound belt over a flattened torus is powered by two independent drive systems. The drive systems are controlled by a combination of infrared cameras and a physical harness system.

Description:
RELATED APPLICATIONS 
     The present application claims priority to U.S. Provisional Application Ser. No. 61/400,535, filed on Jul. 29, 2010, the entirety of which is incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates to a treadmill that can be walked on in any direction without physically moving from one small area. The treadmill of the present invention will be able to greatly enhance the immerging technology of immersive virtual reality along with many other technologies. 
     2. Description of Related Art 
     Several types of omni-directional treadmills or similar functioning devices are known. One such treadmill is disclosed in U.S. Pat. No. 7,780,573 and employs a plurality of high aspect ratio endless unpowered treadmills fixed together transverse to the plane of belt rotation enabling them to move together like the treads of a tank. The plurality of treadmills is then powered by having them pass over several omni-directional wheels that power the multitude of treadmills while allowing them to pass across the omni-directional wheels. 
     Another larger omni-directional treadmill is disclosed in U.S. Pat. Publication No. 20100022358 and uses the same concept of attaching a plurality of endless treadmills together and again move them like the treads of a tank. 
     SUMMARY 
     Unlike the prior art as exemplified by U.S. Pat. No. 7,780,573 which requires multiple belts, the present invention is an omni-directional treadmill that employs only one conveyor belt and is much simpler in nature and simpler to build. Instead of having a separate conveyor belt for each treadmill segment, the omni-directional treadmill of the present invention employs a single conveyor belt. The present invention thereby provides the advantages of not needing an elaborate method to connect end rollers to transfer movement of one belt to the next, thus eliminating the need to individually adjust tensions on a multitude of belts. This single belt is fed from one high aspect ratio cross beam to the next. All cross beams are attached to two common roller chains positioned underneath and near the end of each beam. These common roller chains then move a flat track with sprockets at each end. 
     The cross beams attached to the roller chains are driven by a motor connected to the sprockets the chains go around. This will be referred to herein as the X direction. Y directional movement is produced via omnidirectional wheels placed adjacent to and touching the conveyor belt as it travels around the rollers attached to the cross beam ends. 
     Control for the motors that power the omni-directional treadmill may be accomplished in several ways. One means would be to incorporate an infrared sensing device like an Xbox Kinect to keep track of the user&#39;s direction, speed and acceleration on the treadmill and using that information to keep the user balanced and mostly centered. 
     While this is most likely sufficient for movement, it deprives the user of the inertia the user would normally feel if actually moving. For instance, normally if one were to run at full speed and then abruptly stop without attempting to slow down, one would naturally fall forward or if at full speed one were to quickly change directions without leaning into the turn, one again would fall over. Of course natural balance keeps a person&#39;s feet under their center of gravity so this usually doesn&#39;t happen. 
     On an omni-directional treadmill however, since there is relatively little actual movement, the user would never lean into a turn or have to lean back before stopping even if running fast. This most likely would give the user an inconsistent or slightly disconnected sensation. 
     According to another aspect of the present invention, the omni-directional treadmill is designed such that it can tilt in both the X and Y directions. Tilting control can be tied to the speed controller, enabling the omni-directional treadmill to be programmed to tilt in proportion to a user&#39;s small acceleration. The omni-directional treadmill can be programed to tilt up in the direction of that acceleration if the user was increasing speed and down if reducing speed, tilting as high or low and lasting as long as the controlling acceleration dictates. This tilting forces the user to work a little harder just as if she actually were accelerating her own weight in the direction she was running or turning, giving her the anticipated feeling associated with acceleration. 
     Another or an additional way of controlling the treadmill of the present invention is to use a dynamic control interface. The illustrative control interface described here attaches the user to the machine via a swivel harness. The attachment allows the user to bend forward, sideways, jump up and pivot in any direction. It also allows her limited movement. This movement provides the controller with the user&#39;s position and acceleration. It also allows for a way of dampening her movement to simulate inertia. An additional feature of this system is that it provides a means to modify the user&#39;s apparent weight. She can weigh as much or as little as she desires via the harness interface. And still another feature is that it makes sure that the user cannot accidently run off the platform. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         FIG. 1  is a front view of a person standing on a treadmill constructed in accordance with the present invention. 
         FIG. 2  is a top view of the treadmill of  FIG. 1  in accordance with the present invention. 
         FIG. 3  is a cut away view of a treadmill in accordance with the present invention taken in a direction parallel with the cross beam of the treadmill 
         FIG. 4  is a cut away view of a treadmill in accordance with the present invention in a direction orthogonal to the direction of the cut away view of  FIG. 3  showing the cross beam at the roller chain attach location. 
         FIG. 5  is a cut away view of a treadmill in accordance with the present invention taken in the same direction as the view of  FIG. 4  showing the cross beams at the middle location. 
         FIG. 6  is a partial bottom view of a treadmill in accordance with the present invention showing a group of four cross beams. 
         FIG. 7  is a side view of a single cross beam shown with a conveyer belt. 
         FIG. 8  is a bottom view of four cross beams shown with a conveyer belt threading from one cross beam to another. 
         FIG. 9  is a detailed view cut through a cross beam at a location showing a clip. 
         FIG. 10  is a bottom end view of a cross beam showing a guide bracket with alignment rollers attached 
         FIG. 11  is a cross-sectional view of the cross beam end of  FIG. 10  next to a guide bracket taken through line D-D. 
         FIGS. 12A and 12B  are, respectively, a side view and a front view of an omni-directional wheel. 
         FIG. 13  is a side view of a plastic injection molded cross beam that may be used in a treadmill according to the present invention. 
         FIG. 14  is a cross-sectional view of the cross beam of  FIG. 13  taken through lines F-F at the chain-attach location. 
         FIG. 15  is a cross-sectional view through of the cross beam of  FIG. 13  taken through lines E-E at the center location showing the increased depth of the I beam. 
         FIG. 16  is a top view of the treadmill employing a gimbal for inclining. 
         FIG. 17  is a front view of the gimbled treadmill of  FIG. 16 . 
         FIG. 18  is a side view of the gimbled treadmill of  FIG. 16 . 
         FIG. 19  is a front view of the treadmill showing a dynamic control interface attached. 
         FIG. 20  is a side view of the treadmill having the dynamic control interface of  FIG. 19 . 
         FIG. 21  is a top view of treadmill of  FIG. 19 . 
         FIG. 22  is a detailed view of a hoop-frame floating connection of the dynamic control interface. 
         FIG. 23  is a diagram showing a hoop roller attach point of swivel harness fixture. 
         FIGS. 24A and 24B  are detailed views of a scissor hoop-frame floating connection of the dynamic control interface in an extended and retracted condition, respectively. 
         FIGS. 25A and 25B  are, respectively, top and side views showing a swivel harness assembly attached to user. 
         FIGS. 26A through 26D  are, respectively, top views of the dynamic control interface with a user not moving, the user moving in the X direction, the user moving in the Y direction, and the user rotating. 
     
    
    
     DETAILED DESCRIPTION 
     Persons of ordinary skill in the art will realize that the following description of the present invention is illustrative only and not in any way limiting. Other embodiments of the invention will readily suggest themselves to such skilled persons. 
     Construction and operation of an illustrative treadmill of the present invention is shown in the various views presented in  FIGS. 1 through 7 . The treadmill functions by mounting a series of cross beams  305  on two roller chains  308 , one roller chain near each end of the beam as shown in  FIG. 7 . Cross beams  305  may be formed from a material such as aluminum. The roller chains  308  are assembled to form two parallel chains, each with a sprocket  204  on each end, the sprocket bearings being fixed to a frame  103 . Movement of these beams on the chain assembly allow for movement in the x direction. For movement in the y direction, a single helically wound conveyer belt  313  is employed. Conveyor belt  313  may be formed from polyester monofilament plies with a PVC cover on the top side or equivalent materials. Conveyor belt  313  wraps around rollers  307  placed at both ends of each beam. On the outer surface of each beam the belt is kept in contact along the length of the beam by the beam employing a slight curvature shown at reference numeral  20 . This curvature, which may be about  1 A inch, allows for bowing of the cross beams  305  due to the user&#39;s weight without the conveyor belt  313  lifting off the surface due to a concavity. 
     Cross beams  305  could easily be molded from a thermoplastic plastic material such as Nylon 6/6, and may be shaped as shown at reference numeral  415  in the various views presented in  FIGS. 13 ,  14  and  15 . This version will result in a less expensive, lighter weight and easy to assemble cross beam  305 . 
     The description of movement of the conveyor belt  313  relative to the cross beams  305  will now be described. The conveyor belt  313  travels on the outside of the beam and moves towards the end roller  307 . It then travels around that roller departing it on the inside. The belt  313  then starts a twisting motion while it passes between alignment rollers  318  then through a clip  309  that attaches to the cross beam  305  then on to one of the two roller chains  308  shown in  FIG. 9 . It then pivots slightly around a vertically mounted roller  310  thereby slightly redirecting the belt towards the next cross beam as shown in  FIG. 8 . At this station, the belt has now twisted 90 degrees. The belt then continues twisting and encounters the final roller of the current beam  312 . Each beam has two belt transfers going on at once. One of the rollers  312  is for the conveyer belt moving to the cross beam in front of the current cross beam and the other one of the rollers  312  is for the conveyer belt coming from the cross beam behind the current one. 
     The roller  312  slightly redirects the conveyor belt. Roller  312  allows the belt to stay parallel to the cross beam  305  but held at about the same height as the sprocket teeth roller chain interface. The next roller  312  the belt encounters is parallel to the last one but is mounted on the next beam over. Upon encountering that roller the belt  313  is slightly redirected back down. The belt  313  continues twisting when it encounters another roller  310  that allows it to pivot parallel to longitudinal axis of the new beam. Persons of ordinary skill in the art will note that the conveyor belt has twisted 180° between the two rollers  310 . It then continues with another 90° twist again passing through a clip  309  then alignment rollers  318  mounted on alignment roller holder  317  then encounters the end roller  307  of that beam. A bottom view of this conveyer belting assembly is shown in  FIG. 8 . This somewhat helical wrapping of the conveyer belt  313  repeats for every beam. Therefore, only one (very long) endless conveyer belt is needed to provide y directional movement. The vertical rollers  309  are used to slightly redirect the conveyor belt allowing the end rollers  307  to be oriented exactly 90° from the length of the cross beam to allow the omnidirectional wheels to travel smoothly. 
     When the cross beam/belt assembly is at the end of the flat part of its travel when traveling in the X direction and the roller chain  308  encounters the sprocket  204  it then must rotate. The belt  313  is able to accomplish this because when traveling between cross beams at a location between the pair of rollers  312  it is at the same radius  306  as the roller chain  308  and therefore will simply twist as the two cross beams that it is passing between twist relative to each other as shown in  FIGS. 4 and 5 . 
     The X directional movement is accomplished by powering the axle coupled to the sprockets  204  with an appropriately geared electric motor  104 . Y directional movement is accomplished by omni-directional wheels  102  mounted on four drive shafts  101  geared together and driven by motor  105  with each wheel  102  being pressed into the conveyor belt spinning around the end roller  307 . Since each cross beam  305  has an end roller  307  on each end, inward pressures on those wheels cancel each other out, therefore the amount of pressure exerted on each wheel could be quite substantial if desired, easily enough to produce enough friction to power the conveyor belt in the Y direction, even under high acceleration. The end roller/wheel interface is stabilized by the roller chain assembly on top and ball transfers  311  on the bottom. 
     For additional support, the cross beams are capable of being pinned together, this may be accomplished by attaching a tapered rod  314   a  on one side of the beam and a hole  314  on the other. This will allow each cross beam to provide and get support from the neighboring cross beams on either side, thus making the assembly behave more like a homogeneous structure when the user walks on it. 
     Each cross beam is also provided with a small flange  316  protruding next to the conveyer belt on one side as shown in  FIG. 9 . This flange  316  serves to help prevent the belt  313  from moving off the cross beam. 
     To help reduce noise and vibration, the interfacing sides of the cross beams with the locating pins may be fashioned to have a small gap between them. This gap is to allow for a layer of a resilient material  315  such as rubber to be attached as shown in  FIG. 9 . 
     The omni-directional treadmill of the present invention can easily be mounted on a gimbal  416  or similar device attached to a base  417  and tilted in any direction about pivot points  521  and  522  using linear actuators  418  as shown in  FIGS. 16 ,  17 , and  18  to simulate hills and to allow for an advanced motion control device. 
     Referring now generally to  FIGS. 19 ,  20 , and  21 , an illustrative dynamic control interface includes a floating frame  604  waist high with sliding attachments to four vertical tubes  601 . There is a single cable traveling to all four of the vertical tubes via pulleys  602 . This cable system forces the floating frame to stay level relative to the omni-directional treadmill. The amount of vertical force exerted on the floating frame can be controlled by a piston or actuator  606  connected to one of the vertical tubes  601 . 
     Four bearing blocks  605  glide on the floating frame allowing a means of holding a hoop via four rods  603  or other mechanism such as four scissor connections  616  as shown in  FIGS. 24A and 24B . Two independent cable systems consisting of pulleys  607  and cables  613  connect one side of the hoop to the opposite side. The cables of one system translate during X directional movement and one system&#39;s cables translate during Y directional movement. These systems allows for the hoop to move in the Y direction with no X cable translation and in the X direction with no Y cable translation. The cable for each system runs through its own control unit,  614  for X and  615  for Y as shown in  FIGS. 26A through 26D . The part of the cables that actually run through the control unit may be replaced by a roller chain or other means of mechanically interacting with the control unit. These units may contain an adjustable dampening device which gives the user a sense of inertia. They also easily could provide additional interfaces between the user and the speed control system of the omni-directional treadmill. 
     The user wears a harness  618  which incorporates two side pivot points  611  at the hip locations. These pins attach the harness to the pivot harness assembly  617 . The pivot harness attaches to two hoop roller attach points through front and back swiveling connections  612 . This assembly allows the user to pivot both front and back and sideways.  FIG. 26A  is a top view of the user in the neutral position on the treadmill. She is either not moving or in a steady state of movement.  FIG. 26B  is also a top view and shows the user in a movement in the X direction with a translation in that direction.  FIG. 26C  is a top view showing the user moving in the Y direction with a translation in that direction. The assembly is also capable of twisting inside the hoop  608  via hoop rollers  610  and cable  609  thus allowing the user to turn as shown in  FIG. 26D . 
     Due to the nature of the dynamic control interface, when the user is connected in, she can be made to feel any weight sensation desirable by applying the appropriate force through the vertical actuator  606 . This actuator could be a pneumatic or hydraulic piston connected to a plenum pressurized by a gas. By controlling the gas pressure, someone on the Earth could feel like they were on the Moon or someone on the Moon or in space could feel as if they weighed as much as they desired. 
     To connect to the dynamic control interface, the user first needs to be wearing the harness  618  then, with the swivel harness fixture lowered, simply step into it, pull it up and snap in to the side pivot points  611 . 
     While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications than mentioned above are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except in the spirit of the appended claims.