Abstract:
According to one aspect of the invention, a controllable multi-directional rolling platform for exerting forces on a user is provided comprising a platform contacting a user body part that has a plurality of rolling elements about the periphery of a frame which can rotate along an axis differing from that of the rolling elements, effectively forming a wheel that can roll in two dimensions. The platform is controlled by a computer that uses computing processes to command a signal to a motor, which in turn drives the frame and the rolling elements mounted to it. The platform exerts a force on a user through this action.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/562,347, filed on Apr. 14, 2004, the entire disclosure of which is hereby incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1) Field of Invention  
         [0003]     This invention relates to a system for exerting forces on a user, more particularly one that uses rolling elements.  
         [0004]     2) Discussion of Related Art  
         [0005]     An example of a system that exerts forces on a user using rolling elements is a skateboard. A skateboard, however, is limited to travelling in the direction its wheels are generally pointing. It cannot, for example, roll in the direction of its wheels and simultaneously roll in a direction perpendicular to its wheels. An example of a system that tracks position is a computer mouse. As the user moves his or her hand while resting on the mouse, the mouse reports the position of itself to the computer.  
       SUMMARY OF THE INVENTION  
       [0006]     According to one aspect of the invention, a controllable multi-directional rolling platform for exerting forces on a user is provided comprising a platform contacting a user body part that has a plurality of rolling elements about the periphery of a frame which can rotate along an axis differing from that of the rolling elements, effectively forming a wheel that can roll in two dimensions. The platform is controlled by a computer that uses computing processes to command a signal to a motor, which in turn drives the frame and the rolling elements mounted to it. The platform exerts a force on a user through this action. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The invention is further described by way of example with reference to the accompanying drawings wherein:  
         [0008]      FIG. 138  is a side view of part of wheel assembly  572  capable of rolling across a surface in 2 dimensions.  
         [0009]      FIG. 140  is an isometric view of the components of  FIG. 138  showing how driving motors  558  and  556  drive wheel assembly  572 .  
         [0010]      FIG. 141  is a side view wheel assembly  572  showing how each wheel  542  makes up a section of a complete circle, allowing wheel assembly  572  to rotate continuously.  
         [0011]      FIG. 143  is an isometric view of wheel assembly  572  showing two sets of 3 wheels driven by a motor and tracked with a position sensor.  
         [0012]      FIG. 144  is an isometric view of a user having a force applied to his or her self by means of 3 wheel assemblies  572  mounted to a platform contacting the user.  
         [0013]      FIG. 146  shows an isometric view of a computer mouse that uses wheel assembly  572  to apply forces to a user that grasps it.  
         [0014]      FIG. 147  shows an isometric view of a computer mouse using three wheel assemblies  572  but only driving each with a single motor.  
         [0015]      FIG. 149  is a block diagram of an embodiment that applies forces to a user under computer control. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     One aspect of the invention is shown in  FIGS. 138 and 140 . Wheel  542  is rotably attached to frame  540  and rotates about axis  546 . Pulley  548  drives belt  552  which rides in groove  564  of wheel  542 . Worm gear  554  drives pulley  548  via gear  548   a  rigidly attached to pulley  548 . Worm gear  554  rotates about axis  544 . Frame  540  rotates about axis  544 . Motor  558  drives tube  560  which in turn rotates frame  540 . Motor  556  drives shaft  562  which drives worm gear  554 . It should be noted that worm gear  554  and pulley  548  comprise a transmission unit, and that it is clear that this transmission could be built with different ratios and use different components (for example, a planetary transmission could be attached to motor  556  to provide a different ratio or a bevel gear pair could be used in place of the worm gear and pulley to transmit torque at a 90 degree angle).  
         [0017]     There are actually 6 of assembly  570  arrayed around axis  544  (the 6 have been omitted for clarity), in two sets of 3 equally spaced assemblies that have axis  546  within the same plane, and the two sets (each with the aforementioned plane) spaced apart along axis  544 . The two sets of assemblies are shown in  FIGS. 141 and 143  for additional clarity. As can be seen in  FIG. 143 , the two sets of 3 equally spaced assemblies comprise a first set that includes wheels  542   a ,  542   b , and  542   c  (hidden) and a second set that includes wheels  542   d ,  542   e , and  542   f . Advantageously, a controllable wheel capable of moving in the direction of axis  544  or perpendicular to it is formed. For example, if the array of wheels  542  are on the ground, driving motor  558  causes frame  540  to rotate, which rotates all 6 wheels  542  perpendicular to their axes, forming one large rotating wheel. Driving motor  556  causes worm gear  554  to rotate, thereby causing the 6 wheels  542  to rotate along their axes  546 , causing movement along axis  544 . Since there are separate driving motors  556  and  558 , and since each causes movement of wheel  572  in a different direction than the other, wheel  572  can roll in a 2-dimensional (2D) plane under their power. If one motor is not used in each wheel assembly  572 , for example driving motor  556  is not used and allowed to free-wheel, then wheel assembly  572  can be driven in 1 dimension (1D) by driving motor  558  while being pushed or pulled in the other direction, allowing 2D motion but only being able to control one dimension of it.  
         [0018]     The preferred embodiment of the invention is shown in  FIG. 144 . As shown in  FIG. 144 , three of wheel  572  is attached to platform  576 , which is held to a body part of user  586 , preferably user  586 &#39;s foot using strap  584 . Each of wheel  572  is controlled by control circuit  580 , which is commanded by computer  582 . Since each wheel  572  can be driven in 2D by the driving motors, frame  576  can roll controllably in two directions. By having three of wheel  572 , driving motor  558  of each wheel  572  allows control of platform  576  and user  586  in 2D without the need of driving motor  556  of each wheel  572 . If only one wheel  572  is used, as shown for example in  FIG. 141 , both driving motors  556  and  558  are used so that wheel  572  can be controlled in 2D, allowing platform  576  and user  586  to move in 2D.  
         [0019]     Another embodiment of the invention is shown in  FIG. 146 . Computer mouse  588  has wheel  572  inside it. Mouse  588 , like all computer mice, contains a position sensor to sense the position of mouse  588  on surface  494 . Mouse  588  also has button  571 . The most commonly used method of sensing the position of mouse  588  on surface  494  is by using a ball that is in contact with two rollers that are positioned approximately perpendicularly to each other, as is well known in the prior art. Computer  582  can control mouse  588  through control circuit  580  (just as was seen in  FIG. 144 ). Mouse  588  has a sealing skirt  590  allowing vacuum pump  592  to create a vacuum underneath mouse  588 , so as to pull mouse  588  down to surface  494 . Alternatively, surface  594  is ferrous and mouse  588  is magnetic (for example, a magnet is attached to the bottom of mouse  588 &#39;s housing), so that it is attracted to surface  494 . Advantageously, computer  582  can control mouse  588  and create a force reflection interface out of it, in the same way that platform  576  was controllable via wheels  572  (a force reflection device are described in U.S. Pat. No. 6,339,420, which is incorporated herein by reference). For example, it is apparent that mouse  588  is a specialized form of platform  576 , as user  586 &#39;s body part, in this case his or her hand, is being controllably moved by computer  582  and control circuit  580  via wheel  572  in the same manner that another body part, his or her foot, was controllably moved while attached to platform  576 . When such a platform is accelerated by driving wheel assembly  572  in either embodiment, a force is imparted to user  586 .  FIG. 147  shows magnet  589  pulling mouse  588  down to surface  494 , and it shows how the use of three of wheel  572  can be used on this embodiment as was done in  FIG. 144  in place of the single wheel configuration shown in  FIG. 146  (and in  FIG. 141 ). It also showns an alternative position sensing mechanism known in the prior art consisting of camera  593  and LED  591 , and it showns platform  576  as a part of mouse  588  (for example, platform  576  is a subassembly that snaps into the housing of mouse  588 ). The position of platform  576  (and thus also mouse  588 ) can also be determined by placing optical encoder wheel  595  and optical encoder detector unit  597  on wheel assembly  572  and tracking its rotation about axis  544 , as shown in  FIG. 143 . Such units are well known in the prior art and available from many sources, including U.S. Digital of Vancouver, Wash.  
         [0020]      FIG. 149  shows another embodiment of the invention. Six wheels  542  freely rotate about 6 non-coinciding axes around the periphery of a frame  540  as shown in  FIG. 143 . Frame  540  rotates an axis that is substantially perpendicular to the 6 axes upon which wheels  542  are mounted and is driven by transmission  562 , which is driven by motor  558 . Frame  540  and the six wheels  542  mounted on it comprise wheel assembly  572 . Motor  558  is mounted to platform  576  and driven by control circuit  580 . Platform  576  is touches user  586 . Control circuit  580  is supplied power for motor  558  by power source  577 , which is preferably a rechargeable battery. A position sensor  599  allows control circuit  580  to sense the position of wheel assembly  572  on surface  494 . Computer  582  repeatedly (approximately 1000 times per second is preferred) reads the position data from position sensor  599 , runs a computing process, and sends a signal to control circuit  580 , which in turn uses the signal to set the voltage or current (one determines the other through Ohm&#39;s law of V=IR) of motor  558 .  
         [0021]     While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative and not restrictive of the current invention, and that this invention is not restricted to the specific constructions and arrangements shown and described since modifications may occur to those ordinarily skilled in the art.  
         [0022]     For example, although 6 of wheel  542  have been used in each embodiment, it is possible to use a greater or lesser number of wheels. Likewise, it is possible to use more than 3 of wheel assembly  572  (although using 4 adds complexity, it typically results in greater stability of platform  576  if they are equally spaced about the periphery). Motors  556  and  558  could be replaced by passive components such as friction dampers, magnetorheological fluid dampers, eddy current brakes; particle brakes, etc.