Abstract:
A simulator for snowboarding, skateboarding, water skiing and the like includes a substantially flat board having a support which permits three degrees of freedom of motion. The support can include a convex body which, in combination with a thrust receiving surface, forms a thrust bearing permitting the three degrees of freedom. The support can also include a rotary or turntable type of bearing permitting rotary motion. The simulator is instrumented to measure rotational motion and to provide an output signal compatible with a personal computer (PC) game port or a video game console input/output (I/O) port representative of rotational position of the board.

Description:
This application claims the benefit of provisional application No. 60/103,339 filed Oct. 7, 1998. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The invention relates to sporting apparatus in general and more particularly to sporting apparatus which simulates the motion and sensations of a snowboard, skateboard, water-ski, or other similar sporting apparatus. Yet more particularly, the invention relates to such a motion simulator which can interact with a software program whose display gives a user visual feedback corresponding to movements of a snowboard, skateboard, water-ski or the like. 
     2. Related Art 
     Numerous sporting apparatus are known, including some which require a user to balance on a platform, or the like. For example, snowboards, skateboards and water-skis have a user balance on a platform which is free to move in a range of different directions. In each of these sports, the platform travels through a substantial distance or area, requiring the sport to be practiced either outdoors or in a large facility built for the purpose. For example, snowboarding requires a ski mountain, skateboarding requires a large open space or skateboard park and water-skiing requires a large body of open water. 
     Sports simulation games for personal computers (PCs) or the wide array of video game consoles, such as Nintendo 64, Sony Playstation, Sega Saturn, etc., are constantly striving to achieve greater and greater levels of realistic game play. In order to more fully immerse users in the game-playing environment, game designers have employed ever increasing levels of computer power to provide realistic sights and sounds for the user. However, the physical limitations of common gaming interface devices significantly interfere with a truly realistic gaming experience. Using a keyboard, a mouse, a conventional joystick or even a new generation force-feedback joystick to control for example an alpine snowboarding game, provides only a small fraction of the true physical experience because such controls lack the physical sensations of actually balancing on and controlling the snowboard platform. Some large, substantially non-portable simulators are known for practicing skiing, snowboarding and the like in an arcade environment. See, for example, Shimojima et al., U.S. Pat. No. 5,713,794. Some smaller devices are also known, such as those disclosed by Lipps et al. in U.S. Pat. No. 5,860,861 and Eggenberger in U.S. Pat. No. 4,966,364. However, all of these are either too bulky for home use, do not allow the range of motion inherent to real snowboarding, skateboarding, water skiing or the like, or do not interact with a computer software program to provide visual feedback corresponding to a user&#39;s motions. 
     There is therefore, a need for a device which provides a more realistic simulation of the true physical experience of snowboarding while also being able to interact with the current video gaming platforms such as PCs and video game consoles. Such a device would also allow those new or unaccustomed to the motions required in snowboarding to experience some of the physical sensations of the sport without the dangers inherent in such an activity. 
     SUMMARY OF THE INVENTION 
     An exercise device simulating a snowboard according to some aspects of the invention may include a platform; and a support including a thrust bearing, connected to the platform to permit three degrees of motion. The thrust bearing of the device may further comprise a body having a generally convex surface extending downwardly. The support of the device may further comprise a rotary bearing connecting the platform to the body for rotary motion. The device may include a position detector having an output connectable to a PC game port or a position detector having an output connectable to a video game console I/O port. 
     A method of simulating a physical activity according to other aspects of the invention may include steps of allowing movement in a measured direction; and facilitating the allowed movement by allowing additional movement in an unmeasured direction. The method can be practiced wherein the measured direction is rotary and the unmeasured direction is tilting. 
     In a game playing peripheral apparatus which supports a person, embodiments of the invention can include a support for the apparatus having three degrees of freedom and one measured direction of motion. The support may further comprise a body having a generally convex surface extending downwardly, and may further include a rotary bearing connecting the platform to the body for rotary motion. There may also be a position detector oriented to the measured direction, having an output connectable to a PC game port or a position detector oriented to the measured direction, having an output connectable to a video game console I/O port. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, in which like reference designations indicate like elements: 
     FIG. 1 is a perspective view of one embodiment of a snowboard simulating device; 
     FIG. 2 is an exploded view of the device of FIG. 1; 
     FIG. 3 is a perspective view of a skid plate for the device of FIG. 1; 
     FIG. 4 is a pictorial view of an interface circuit connecting the device to a PC or video gaming console; 
     FIGS. 5 and 6 are exploded views of alternate embodiments of the device; and 
     FIG. 7 is a pictorial view of an auxiliary hand control. 
    
    
     DETAILED DESCRIPTION 
     The invention will be better understood upon reading the following detailed description of some embodiments thereof in connection with the accompanying figures. 
     As shown in FIG. 1, a snowboard simulator apparatus  101  features a generally rectangular top platform  103  on which the user stands with one foot positioned in front of the other at about shoulder width apart  104  (see FIG.  2 ). A convex body  105  is mounted to the top platform at a point between the intended positions of the users feet via a turntable-style bearing assembly  107 . The mount point is preferably ⅔ of the way from the rear of the board. Moving the mount point to ⅓ of the way from the rear simulates surfing or skateboarding posture. The body  105  is preferably about 7 ½″ diameter, 1″ thick and having about a 1″, ¼-round edge radius. A curved skid plate  109 , located near the rear  111  of the simulator apparatus  101  allows the device to sit flat on the ground, yet still tilt A—A from side to side. As a user leans forward while standing on the apparatus the weight of the user is unloaded from the skid plate  109 , allowing the device to more easily rotate B—B. The rotation B—B may be facilitated by movement of the turntable-style bearing  107  or by pivoting of the convex body  105  about a contact point with the ground. 
     Rotation of the board  101  about an axis between the user&#39;s feet has been found to be much more realistic than rotation about other axes, such as one placed forward of the device. Also contributing to the realism of the physical experience using the board  101  is the convex shape of body  105 . The body  105  is convex around its entire surface, allowing the user to pivot in any direction while simultaneously rotating the board  101  in direction B—B. 
     In an embodiment of the device suitable as an input device to a PC or video gaming console, a dual channel optical encoder  113  or other rotary position sensor monitors the relative rotation B—B of the top platform  103  with respect to the convex body  105  which remains stationary relative to the ground during use of the board  101 . The encoder should have a resolution of about 100 positions/180°, although more or less can also be used. During actual use, only about ±45° of movement occurs. The encoder could have a higher resolution, adjusted down by software executing on a microprocessor, the microprocessor embedded in an interface circuit such as described below in connection with FIG. 4, thus providing calibration. Also, a centering device, such as an elastic band or spring tying the body  105  to a fixed point on the board  103  should be provided. The centering device insures that the position sensor reports a reference position during calibration, when the position is not influenced by motion of a user. Additionally, thin film pressure sensors, membrane switches or other, similar devices (not shown) applied to contact surfaces of the convex body  105  and skid plate  109  are used to monitor the contact of the rear skid plate  109  and the convex body  105  with the ground on which they rest, thereby providing edging information to snowboard simulator software running on the PC or video game console. The information from the various sensors is read by the system electronics which connects through an input/output port of the PC or the video game console system. 
     Embodiments and aspects of the invention are now described in greater detail. 
     As shown in the exploded view of FIG. 2, the snowboard simulator apparatus consists of a top platform  103 , rear skid plate  109 , turntable bearing assembly  107 , encoder wheel  201 , convex body  105 , dual channel optical sensor  203  and support bracket  205  (optical encoder  113  comprised of the elements  201 ,  203  and  205 ). 
     The top platform  103  is generally rectangular in shape and similar in appearance to a skateboard or snowboard. In one embodiment of the device, the top platform  103  is fabricated from ½″ thick, high quality plywood with dimensions of 10″ by 24″. Plastics, fiberglass, composites and other materials known to the skilled artisan could also be used for the platform. It is understood that the platform could be manufactured using a wide range of methods and materials while achieving basically the same function. Although the top platform  103  should be basically flat, the ends can be curved, upturned or otherwise shaped for cosmetic appearance or to simulate the platform shape of a particular snowboard, skateboard or other device. 
     The skid plate  109 , as shown in FIG. 3, features a curved plastic surface  301  which slides smoothly when in contact with materials such as carpeting. The illustrative embodiment of FIG. 3 features a wood block  303  overlaid by a Delrin sheet  305 . However, the skid plate  109  could be made of solid wood or molded plastic such as Teflon, or could be another solid substrate overlaid by any suitable low friction material, including Teflon. 
     In one embodiment of the snowboard apparatus, thin film tactile sensors (not shown) are mounted between the Delrin sheet  305  and the wood block  303  that make up the rear skid plate  109 . In this configuration, the sensors have outputs which indicate the side to side tipping of the device  101 . Detection of the side to side tipping triggers routines in one embodiment of the software which simulate the effect of edging. It is understood that other force sensing devices, membrane switches or other technologies could also be used to provide the same function. It is also understood that similar sensors could be used on the convex body to allow edging and front to back weight distribution to be monitored. Such information could be used by the software to compute and display a realistic body position for an on-screen simulated rider. 
     The above described sensing devices determine the motion of the snowboard apparatus in real space, so that motion can be simulated in a virtual world represented by the software. To this end, other position indicating methods can be used, for example laser or radio triangulation, magnetic field manipulation or robotic vision systems could be employed to determine the position of the snowboard apparatus. Other technologies available to monitor the rotation of the convex body relative to the top platform include but are not limited to potentiometers, hall effect sensors, magnetic induction methods and the like. 
     The position sensor connects to a PC or video game console through an interface circuit  401  such as that shown pictorially in FIG.  4 . The circuit shown features an 8 bit microcontroller U 1  and a digital potentiometer U 2 . The interface circuit  401  produces at least one output  403  which represents the position of the snowboard apparatus as a signal similar to that which a joystick produces to represent the position of the joystick. Thus, the snowboard apparatus  101  can connect directly to the game port of a PC, which is the I/O port to which a joystick is normally connected. The interface circuit firmware is responsible for reading the various sensors on the snowboard simulator and translating them into the appropriate joystick outputs. It should be understood by those skilled in this art that although the circuit illustrated connects the snowboard apparatus  101  to a PC game port, only slight modifications are required to connect the snowboard apparatus  101  to various video gaming console systems, such as Nintendo 64, Sony Playstation, Sega Saturn, etc. 
     FIG. 5 presents an alternative embodiment of the snowboard apparatus in which the rear skid plate (FIG. 1,  109 ) has been replaced by a series of wheels or rollers  501  mounted in a frame  503 . Although three rollers  501  are shown in the drawing, it is understood that either more or fewer wheels or rollers could be used. Like the skid plate  109 , the rear roller assembly  505  can be instrumented with strain gauges, thin film force sensors or the like to determine how the operator is edging. This information can be used by the system software to influence the speed and direction of the virtual movement, i.e., the speed and direction of the movement displayed by the software to the user. Moreover, instead of a single assembly of rollers  505 , as shown, two casters can be mounted at or near the rear corners of board  103 . The wheels at the rear can instead be fixed wheels with their axles aligned with the center of rotation of the board  103 . Alternate rear support designs which support the back of the board  103 , but allow rotary motion of the board when slightly unweighted should now be evident to the skilled artisan. 
     FIG. 6 presents still another alternative embodiment of a snowboard apparatus  601  in which the device  601  has been divided into two sub-assemblies  603 ,  605 . One sub-assembly is a passive board assembly  603  which can be used independently. The other sub-assembly is an instrumented turntable  605 . As shown in FIG. 6, the turntable assembly  605  features an optical encoder  113  or other sensor which produces an output signal representing the angular orientation of the device, similar to the integrated systems described above. 
     The board assembly includes a fixed, convex body  607  and one or more rear rollers or a skid plate, as described above. Therefore, the device is capable of both the front-to-back and side-to-side motion required. In one version of this device, the passive snowboard assembly  603  connects to the instrumented turntable  605  by a pin  609  having a square or rectangular cross-section. This pin mates to a complementary shaped hole  611  in the bottom of the convex body  607  of the snowboard assembly  601 . The hole  611  has tapered sides, to accommodate front-to-back and side-to-side tilting of the board while still transferring the angular position of the board to the top portion  613  of the turntable  605 . The amount of tilting can be monitored by thin-film force sensors or the like located on the top portion  613  of the turntable assembly  605 . The top portion  613  of the turntable assembly  605  is connected to the turntable-type bearing  107  through mounting disk  615 . Turntable-type bearing  107  is mounted to a base  617  which rests on the floor, for example, or is mounted to other components if desired. 
     It should be understood that numerous other methods are available for physically linking the board and turntable including friction methods, Velcro, and magnetic clutches. Additionally, the passive snowboard assembly can be used without the turntable if the snowboard assembly includes directional sensors or transducers such as gyroscopic, magnetic induction, RF triangulation, GPS, or accelerometer devices. 
     The system can further include an Auxiliary Hand Controller (AHC) connected to the interface circuit of FIG. 4 to provide button inputs and y-axis control. The Auxiliary Hand Controller (AHC), shown in FIG. 7, allows the user to access menu items and control certain trick motions while riding the board  103 . In addition, the AHC provides the y-axis input sometimes required when using the board with 3rd party software titles, Sierra&#39;s Ski Racing, for example. The AHC shown in FIG. 7 includes two buttons  701  and a y-axis variable input  703 . The AHC is connected to the interface circuit in a conventional manner using any suitable connector. 
     Some embodiments of the invention use two especially advanced pieces of software technology. First, there&#39;s the terrain engine, and second, there&#39;s the physics and animation of the boarder. 
     The terrain engine is capable of handling vast chunks of real-world topography, while allowing the level designer fine control over small details like moguls and jumps. The renderer automatically breaks the terrain into triangles on the fly to keep things looking good at a decent frame rate. The engine only uses triangles where it needs them. Mountains in the background of a rendered scene are actually rendered in 3D, not painted onto a flat backdrop. The entire terrain is rendered as a single, continuous mesh, covering a 64 km×64 km area. The other major piece of advance tech is the boarder physics/control/animation. The boarder is a true virtual snowboarder, bound by realistic board and figure physics, and animated completely in real time in response to user input and conditions in the game world. 
     The physics are fairly detailed, and so in order for the boarder to get down the mountain, there&#39;s a sophisticated controller layer that mediates between the inputs from the user and the physics of the engine. So when the user presses a button to make the boarder jump, the controller had to change the leg forces of the simulated figure, which feeds into the physics model and causes the figure&#39;s legs to push against the ground, resulting in vertical motion. Similarly, to keep the boarder from falling over, the controller has to continuously monitor the balance of the figure and in turn adjust the angle of the board, the center of mass of the figure in relation to the board (by moving the figure&#39;s legs and torso), as well as the downward leg forces. There&#39;s no motion capture or canned animation whatsoever. As a result the animation is far more realistic than a conventional snowboarding video game. When the boarder jumps, it looks like a jump because all the relevant forces are being modeled; when he falls down, it&#39;s because he just couldn&#39;t stay upright due to the terrain conditions, his linear and angular momentum, and the input from the user. 
     The present invention has now been illustrated by the description of several embodiments thereof. Numerous variations and other embodiments, incorporating the principles of the invention which will now be apparent to those skilled in the art are contemplated as falling within the scope of the invention, which is limited only by the appended claims and equivalents thereto.