CONTINUOUS OMNIDIRECTIONAL TREADMILL APPARATUS

Abstract

The disclosed method comprises a hollow, spherical treadmill belt which envelops an internal treadmill deck. The belt is not held flat and under tension over the treadmill deck by being stretched tightly around it, but is instead loosely fit around the treadmill deck and is pulled flat and tensioned by a separate system comprising low-friction rings, which redirect the treadmill belt, analogous to a three-dimensional pulley system. A motorized drive system utilizes electric motors, each coupled to an omniwheel, which can drive the treadmill belt in one direction while allowing it to move freely in a perpendicular direction. Sensors are placed across the treadmill belt to detect lateral forces applied to the surface by the user; data from these sensors is used to keep the user centered on the surface of the omnidirectional treadmill.

Claims

1. An omnidirectional treadmill device comprising: an internal treadmill deck; a hollow, spherical treadmill belt which loosely envelops the internal treadmill deck such that the hollow, spherical treadmill belt is not held under tension by the internal treadmill deck alone; a treadmill belt management system configured to tension the hollow, spherical treadmill belt and pull a portion of that hollow, spherical treadmill belt flat over the top surface of the internal treadmill deck; the treadmill belt management system comprising a plurality of low friction rings configured to act as omnidirectional pulleys, redirecting the hollow, spherical treadmill belt between that plurality of low friction rings; a treadmill deck support system comprising a plurality of ball transfers configured to secure the internal treadmill deck through the hollow, spherical treadmill belt without inhibiting movement of that hollow, spherical treadmill belt; a motorized drive system comprising at least one electric motor coupled to an omniwheel external to the hollow, spherical treadmill belt, with each motor coupled external omniwheel being paired with a, freely rotatable, internal omniwheel such that the hollow, spherical treadmill belt is frictionally engaged between the outer edges of each pair of external and internal omniwheels; and a lateral force detection system comprising at least one sensor configured to detect a magnitude and direction of translational forces imparted by a user onto the hollow, spherical treadmill belt.

2. The omnidirectional treadmill device of claim 1, wherein the hollow, spherical treadmill belt comprises a hollow sphere of rubber, plastic, fabric, or any combination thereof with the diameter of the hollow sphere being greater than that of the internal treadmill deck.

3. The omnidirectional treadmill device of claim 1, wherein at least one of the low friction rings is below the internal treadmill deck.

4. The omnidirectional treadmill device of claim 1, wherein each of the low friction rings comprise a plurality of radially spaced omniwheels, thereby reducing sliding friction.

5. The omnidirectional treadmill device of claim 1, wherein the treadmill deck support system comprises a plurality of ball transfers positioned both on an interior and exterior of the hollow, spherical treadmill belt such that each ball transfer is pinned in place by a pair of opposite ball transfers through the hollow, spherical treadmill belt.

6. The omnidirectional treadmill device of claim 1, wherein each of the external and internal omniwheels of the motorized drive system comprise a single circumferential row of rollers capable of maintaining continuous frictional engagement with the hollow, spherical treadmill belt between each pair of external and internal omniwheels.

7. The omnidirectional treadmill device of claim 1, wherein the lateral force detection system comprises at least one sensor frictionally engaged with the hollow, spherical treadmill belt, with the at least one sensor configured to detect translational forces applied to the hollow, spherical treadmill belt.

8. The omnidirectional treadmill device of claim 7, wherein the at least one sensor comprises a plurality thereof; wherein each sensor is configured to detect both static and dynamic forces applied to the hollow, spherical treadmill belt in a given direction; and wherein a combination of the plurality of sensors thereby enabling complete omnidirectional detection of horizontal forces imparted on the hollow, spherical treadmill belt by a user.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is an exploded perspective view illustrating the assembly of various major components of an omnidirectional treadmill, illustrating the manner in which the choke ring wraps around the treadmill belt and the components enveloped by it.

[0009] FIG. 2 is an exploded perspective view illustrating the assembly of an omnidirectional treadmill, illustrating the manner in which the treadmill deck support system and motorized drive units are assembled and interlocked with the assembly from FIG. 1.

[0010] FIG. 3 is a perspective view of a fully assembled omnidirectional treadmill with the treadmill belt enveloping the treadmill deck and its affixed components.

[0011] FIG. 4 is a cross-sectional side view of the omnidirectional treadmill of FIG. 3.

[0012] FIG. 5 is an isolated cross-sectional side view of the omnidirectional treadmill of FIG. 3, displaying how the components which constitute each motorized drive unit interact with the treadmill belt, with a magnified, partial cross-sectional detail view of one of the ball transfer assemblies which compose the treadmill deck support system.

[0013] FIG. 6 is a perspective view of a C-clamp assembly carrying an electric motor with a motor-driven omniwheel.

[0014] FIGS. 7A and 7B respectively are a perspective view and a cross-sectional front view of one of the four magnetic suspension units within the treadmill deck support system, with the treadmill belt omitted for purposes of readability.

[0015] FIG. 8 is a partial cross-sectional front view of a continuous edge omniwheel.

[0016] FIG. 9 is a partial cross-sectional front view of one of the auxiliary omniwheels which partially compose the rings in the treadmill belt management system.

[0017] FIGS. 10A and 10B respectively are an undeformed illustration of the icosidodecahedral construction of the treadmill belt and an illustration of the motion induced into that treadmill belt at various points about its topology.

[0018] FIG. 11 is a block diagram illustrating the function of the, closed loop, belt control system.

[0019] FIG. 12 is a cross-sectional side view illustrating the negative effects of stretching a relatively small spherical treadmill belt around a larger, disk-shaped treadmill deck.

DETAILED DESCRIPTION

[0020] The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings. This present disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiment set forth herein. Rather, this embodiment is provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. Like numbers refer to like elements throughout, with base 100 reference numerals used to indicate the subsystem assemblies which collectively constitute the omnidirectional treadmill 1000 apparatus.

[0021] The present disclosure contains an omnidirectional treadmill 1000 design which utilizes external electric motors 511 to control a continuous movable surface. These electric motors 511 can be made as large and powerful as desired, thereby enabling the potential for high-speed movements across the treadmill belt 100. To allow for a spherical treadmill belt 100 to be controlled in this manner, two critical omnidirectional movement components were utilized.

[0022] The first critical omnidirectional movement component is a device called an Omniwheel, depicted in FIGS. 8 and 9. An omniwheel is a wheel with smaller rollers around its circumference to allow for smooth movement in multiple directions across the edge of the wheel. The axis of rotation of the rollers is perpendicular to the axis of rotation of the omniwheel as a whole. Omniwheel 520 has a nearly continuous edge, while omniwheel 321 has rollers 323 with significant gaps between them.

[0023] The second omnidirectional movement component, called a ball transfer, is depicted in the detail view within FIG. 5. A ball transfer 422 is an omnidirectional load-bearing spherical ball 423 mounted inside a restraining fixture 424.

[0024] The construction of this omnidirectional treadmill 1000 embodiment is conceptually similar to that of a traditional treadmill; with both being designed for a user to walk or run on a motor-driven treadmill belt 100 which is wrapped around a supporting treadmill deck 200. However, significant changes must be made to this general concept to allow for omnidirectional movement capabilities.

[0025] Firstly, instead of the continuous circular strip of material used in a traditional treadmill, a hollow sphere of material can be used as the treadmill belt 100 to enable continuous omnidirectional movement. Unfortunately, this hollow sphere would fully envelop the treadmill deck 200, which removes the ability to easily support the treadmill deck 200 from the sides, as would be done with a traditional treadmill. Similarly, any electric motors 511 would need to be moved outside of the treadmill belt 100, as a power cable could not easily be run through the treadmill belt 100 without inhibiting its movement. Lastly, the method for having the treadmill belt 100 pulled flat and under tension over the treadmill deck 200 must be drastically different from a traditional treadmill. This is because a hollow sphere of material does not behave similarly to an already flat strip of material, like that of a traditional treadmill's belt, in regard to conforming to a flat surface. The novelty of the present disclosure derives from the solutions chosen to address these problems.

[0026] The treadmill belt management system 300 was created to address the issue faced by alternative omnidirectional treadmill 2000 designs wherein the spherical belt 2100 does not properly conform to the surface of the treadmill's platform 2200. Intuitively, one might think that such a spherical belt 2100 could easily be stretched around a disk-shaped platform 2200 such that the spherical belt 2100 is pulled flat solely by the tension provided from being stretched around that relatively larger platform 2200. However, testing has revealed that this is not how a spherical belt 2100 behaves in reality. If a hollow sphere constructed from a flexible material is pulled taught around a platform 2200 with a diameter greater than that of the spherical belt 2100, the center of the sphere vertically aligns itself with the widest part of the platform 2200 to minimize tensile forces 2110, therefore leaving the entire top hemisphere of the spherical belt 2100 to be flattened. The contour of that hemisphere has areas towards the top which are already nearly tangentially flat over the platform 2200, while having areas towards the edges which are nearly tangentially perpendicular to the surface of that platform 2200. As is illustrated in FIG. 12, this results in extremely uneven tensile forces 2110 across the spherical belt 2100, producing unreasonably high tensile forces 2110 around the edges of the platform 2200, while having almost no tension towards the center. To address this issue, the present disclosure utilizes a treadmill belt 100 with a spherical diameter greater than the diameter of the treadmill deck 200 which it envelops. This decision was made after it was calculated that, for a two-times increase in sphere diameter relative to platform diameter, the treadmill belt 100 becomes well over ten-times easier to flatten over the treadmill deck 200. This larger and more loosely fit treadmill belt 100 is spatially managed and pulled under tension by the treadmill belt management system 300.

[0027] The treadmill belt management system 300 is analogous to a three-dimensional pulley system, with its constituent rings 320 guiding the treadmill belt 100 like how pulleys might redirect a traditional belt. The treadmill belt management system 300 consists of two rings 320 with a diameter slightly larger than that of the treadmill deck 200, with a, significantly smaller, choke ring 330 in between them, with the choke ring 330 acting as the three-dimensional equivalent of a belt tensioner. The uppermost ring 320 guides the treadmill belt 100 such that it is held slightly above the surface of the treadmill deck 200, with the belt and deck only coming in contact when a user's weight locally presses them together. The upper and lower most rings 320 consist of a plurality of radially spaced omniwheels 321, as opposed to a more simple, smooth, low-friction hoop. This was done to minimize friction, with each omniwheel 321 acting as a bearing to prevent sliding friction, similar to how bearings are used in traditional pulley systems, but adapted for omnidirectional operation. The choke ring 330 consists entirely of traditional deep-groove ball bearings 331 with minimal gaps between them, with the minimized gaps being necessary to prevent the treadmill belt 100 from jamming between each ball bearing 331, and with ball bearings 331 being usable due to the choke ring 330 being vertically positioned around the topological center 130 of the treadmill belt 100. Perhaps the best visualization of the treadmill belt management system 300 is in FIG. 4, where the cross-sectional illustration makes the pulley system analogy become obvious.

[0028] The motorized drive system 500 is used to move the treadmill belt 100 across the treadmill deck 200. This system consists of four separate motorized drive units 510, with each motorized drive unit 510 consisting of a single electric motor 511 which is coupled to an omniwheel 520, with both the electric motor 511 and omniwheel 520 being located external to the treadmill belt 100. Each external omniwheel 520 is paired with a, freely rotatable, internal omniwheel 520 such that the treadmill belt 100 is pinched and frictionally engaged between the edges of each pair of omniwheels 520. For this to be possible, the omniwheels 520 used in the motorized drive system 500 must have a continuous edge such that frictional engagement with the treadmill belt 100 is never lost. The omniwheel depicted in FIG. 8 has just that, comprising a web 521 which holds a single circumferential row of rollers 522 with minimal gaps between adjacent rollers 522, as opposed to more traditional omniwheels 321, where the construction of the web 322 and rollers 323 leaves significant gaps. The reason an omniwheel 520 is used to drive the treadmill belt 100 instead of a traditional wheel is because an omniwheel 520 has rollers 522 around its circumference which rotate in a direction perpendicular to the axis of rotation of the omniwheel 520 as a whole. This enables the motorized drive system 500 to have 2 pairs of motorized drive units 510 configured perpendicular to one another such that each pair of motorized drive units 510 can be frictionally engaged with the treadmill belt 100 in a single direction, while simultaneously allowing the treadmill belt 100 to pass freely between its omniwheels 520 in a direction orthogonal to that. The result of this is that both pairs of motorized drive units 510 can operate independently of each other to move the treadmill belt 100 in each of their own directions, with all oblique directional movements becoming achievable by having both pairs of motorized drive units 510 operating simultaneously, with their relative speeds determining the obliquity of the resultant horizontal movement 110 vector.

[0029] For the treadmill belt 100 to be capable of moving continuously, the weight of the treadmill deck 200 must be supported through the treadmill belt 100 without impeding its movement. To accomplish this, four magnetic suspension units 430 are located underneath the treadmill deck 200. A magnetic suspension unit 430 is illustrated in FIG. 6A and in FIG. 6B. Each magnetic suspension unit 430 consists of a set of magnets 433 fixed within the treadmill belt 100 and underneath the treadmill deck 200, with a corresponding set of magnets 433 located outside of the treadmill belt 100. The internal magnets 431 and external magnets 432 are configured to repel each other, thereby enabling a contactless transfer of the weight of the treadmill deck 200 into the ground through the magnetic repulsion force 434. The external component of each magnetic suspension unit 430 has two rows of magnets 433, which allow the internal magnets 431 to remain stable and centered relative to the external magnets 432, especially when high-load conditions push them close together.

[0030] To properly secure the position of the treadmill deck 200 relative to the external environment, four C-clamp 420 units are used. FIG. 6 includes a depiction of a C-clamp unit. The C-clamp 420 assemblies collectively serve the purpose of preventing undesired movements of the treadmill deck 200, while each individual C-clamp 420 simultaneously acts as a mounting point for a single electric motor 511 and accompanying omniwheel 520. Each C-clamp 420 assembly is indirectly connected to the treadmill deck 200 through the treadmill belt 100 via a set of ball transfers 422 located both internal and external to the treadmill belt 100 such that each set of external ball transfers 422 pin the internal one in place, or vice versa. The use of ball transfers 422 allows for a strong connection to be formed through the treadmill belt 100 without impeding the belt's movement in any direction. The C-clamp 420 assemblies are also connected to an external structural frame 410 via a set of rods 425 and linear bearings 426 which restrict all non-vertical movements of the C-clamp 420 relative to the structural frame 410. Due to the C-clamp 420 retaining the ability to move freely up and down, the weight of the C-clamp 420 rests on the edge of the affixed omniwheel 520, with the mounted height of that omniwheel 520 relative to the C-clamp 420 determining the gaps between the upper and lower ball transfer assemblies 421, with it being desirable for the upper and lower ball transfer assemblies 421 to have an equal gap for the treadmill belt 100 to pass through. The weight of the C-clamp 420 resting on the edge of the affixed omniwheel 520 necessitates an additional consideration, which relates to the traction of the motor driven omniwheels 520 being limited by the weight of the C-clamp 420. In this embodiment, each C-clamp 420 has an affixed cylindrical chunk of steel 427, which is used as a weight to ensure sufficient traction between the omniwheels 520 and the treadmill belt 100. The ball transfers 422 and linear bearings 426 enable the C-clamp 420 assemblies to act as a link between the treadmill deck 200 and the structural frame 410, only allowing the treadmill deck 200 to move vertically on the magnetic suspension units 430, while preventing all other movements. The C-clamps 420, magnetic suspension units 430, and the structural frame 410 form the treadmill deck support system 400, which maintains the edge-alignment of the internal and external omniwheels 520 from each motorized drive unit 510 while simultaneously ensuring the magnetic suspension units 430 are properly vertically aligned.

[0031] As previously mentioned, the treadmill belt 100 is driven by two orthogonally oriented pairs of motorized drive units 510, with each pair operating in series to cooperatively move the treadmill belt 100 in-line with themselves. This motorized drive system 500 produces purely planar horizontal movements 110, allowing the surface of the omnidirectional treadmill 1000 to be translated freely in any horizontal direction across the treadmill deck 200, with rotational motion of the treadmill belt 100 relative to the center of the treadmill deck 200 being intentionally omitted from the system's capabilities. Rotational capabilities were omitted in order to significantly reduce complexity and cost, with the choke ring 330 design receiving a disproportionate benefit from this decision. The choke ring 330 is able to consist of a plurality of traditional deep-groove ball bearings 331 instead of the omniwheels 321 which are used on the upper and lower rings of the treadmill belt management system 300. These traditional ball bearings 331 can be used in lieu of an omnidirectional alternative due to the choke ring 330 being vertically positioned around the topological center 130 of the treadmill belt 100. The reasoning for this allowance becomes apparent upon viewing FIG. 10B, wherein the relative topological movement of the treadmill belt 100 is illustrated in its undeformed, spherical state, with arrows representing the direction of movement of the treadmill belt 100 at various critical points. FIG. 10B displays that, for any horizontal movement 110 at the top of the sphere, there will only be perfectly vertical movement 120 along the line which separates the top and bottom hemispheres. Therefore, so long as the choke ring 330 is vertically situated about the topological center 130 of the treadmill belt 100, traditional ball bearings 331 will operate properly to minimize friction, while gaining the additional benefit of being far more compact than any omnidirectional alternative. This compact quality lends itself nicely to the function of the choke ring 330, which necessitates minimal gaps between each of the ball bearings 331 to prevent the treadmill belt 100 from being pinched between them. The reason for this particular concern is that the choke ring 330 guides the widest part of the topology of the treadmill belt 100 through the ring of the treadmill belt management system 300 with the smallest diameter, which necessarily leads to panels 140 on the treadmill belt 100 becoming scrunched up in this area, with folded panels 140 having the potential to introduce high resistive forces if squeezed into a gap between the ball bearings 331. Interestingly, the choke ring 330 being tightened around the treadmill belt 100 naturally results in forces which push it toward the position where the cross-sectional circumference of the topology of the treadmill belt 100 is greatest, therefore causing it to naturally drift to the desired position.

[0032] Though it could theoretically be constructed from alternative materials, in this embodiment, the treadmill belt 100 was constructed from a thin, plastic-backed fabric assembled in the shape of an icosidodecahedron. This specific polyhedron was chosen due to its ability to be constructed from 6 separate continuous strips of fabric 150, with flat panels 140 interconnecting them (Seen in FIG. 10A). The importance of this construction lies in the desirability of a consistent treadmill belt 100 thickness with no sharp corners between panels 140, with these attributes leading to ideal and predictable behavior. Consistent thickness was achieved by having panels 140 constructed of two layers of plastic-backed fabric, with the plastic sides of each layer facing each other. The innermost layer of each of the panels had each of its sides extended out by an amount which was half of the width of the continuous strips of fabric 150 such that the edges of the innermost layers of two adjacent panels 140 were able to be abutted, with the continuous strips of fabric 150 being able to fit nicely in the resultant gap in the outermost layer. This allowed the continuous strips of fabric 150 to act as a bridge between panels 140, with the inner and outer layers being combined using a heat-press to melt the plastic-backed sides of each layer together, fusing the outer and inner layers to create one unified treadmill belt 100 of a consistent thickness. This simple construction has a constant thickness and no sharp corners, which leads to a treadmill belt 100 which easily conforms to the flat shape of the treadmill deck 200, while having predictably consistent interactions with the omniwheels 520 and ball transfer assemblies 421.

[0033] The assembly of this omnidirectional treadmill 1000 embodiment will now be described in detail, beginning with the assembly of the treadmill belt 100 and the components which reside within it, with this section of assembly being illustrated in FIG. 1. In this embodiment, the treadmill deck 200 and treadmill belt management system 300 were constructed separately before both being unified and enveloped by the treadmill belt 100, with the treadmill deck 200 consisting of a circular wooden tabletop 210 with friction minimizing components screwed into it, and the treadmill belt management system 300 consistent of a welded frame 310 with various components bolted to it. This treadmill deck 200 was constructed from a wooden tabletop 210 with a diameter of roughly five feet, with wood being used in this case due to the experimental nature of this embodiment, where the ability to frequently rearrange and refasten components to its surface was desirable. The components affixed to the surface of this wooden tabletop 210 were used as bearings with the purpose of minimizing friction in any direction a user might walk across the surface of the omnidirectional treadmill 1000. To accomplish this, a series of plastic rollers 220 of varying lengths were affixed to the outer confines of the treadmill deck 200, with those rollers providing a low friction centripetal or centrifugal path for any outer position which a user's foot might reasonably find itself in. The plastic rollers 220 were used in combination with a central, planar bearing 230, which essentially constitutes hundreds of omnidirectional load-bearing spherical balls 423 which are all mounted within a single restraining fixture 424, which was additively manufactured in this case, with the spherical bearing balls being cheaply acquired and utilized in its final assembly. The planar bearing 230 is used for its omnidirectional friction minimizing capabilities in the radially central area of the treadmill deck 200 where a user's feet are not necessarily going to be moving in a centripetal or centrifugal path due to the breadth of a user's stance not being infinitely small nor perfectly centered. That treadmill deck 200 is then bolted to the top of the welded frame 310 of the treadmill belt management system 300, which is itself constructed from, radially spaced, welded steel pipes 311, with the rings of omniwheels 321 being affixed to the ends of these pipes, with four sets of continuous omniwheels 520 and ball transfer assemblies 421 mounted similarly. Additionally, the internal magnets 431 of the four magnetic suspension units 430 are mounted on the bottom of the welded frame 310. The treadmill deck 200 and the other internal components are then enveloped by two halves of the treadmill belt 100, as illustrated in FIG. 1, with those halves being heat-sealed around the internal assembly with a specialized tool. This treadmill belt 100 is then tensioned around the internal components by the choke ring 330, which is initially in multiple parts which are all secured together by a long hose clamp, with that hose clamp being tightened until the separate parts of the choke ring 330 have all been brought together around the topological center 130 of the treadmill belt 100.

[0034] The assembly of the components of this omnidirectional treadmill 1000 embodiment which are external to the treadmill belt 100 can be accomplished in various orders, but the order which was found to be the most effortless will now be described as depicted in FIG. 2. A structural frame 410, which was welded from steel, is split into two identical halves. Each half has an assortment of vertically oriented linear bearings 426 bolted to it, with the C-clamps 420, accompanying electric motors 511, and driven omniwheels 520, sliding smoothly into those linear bearings 426 before being locked in place by additional sets of linear bearings 426 which slide over the top of the rods 425 on the C-clamps 420, securing them to the structural frame 410.

[0035] Each half of the structural frame 410, with each accompanying pair of C-clamps 420, is then slid together around the treadmill belt 100 and its internal components, with the ball transfer assemblies 421 interlocking and securing the relative positions of all components. To accomplish this in reality, the C-clamps 420 are temporarily widened by mechanical spreaders which allow the ball transfer assemblies to interlock, though this is not how the C-clamps 420 were designed to be installed, this method was found to be the fastest and easiest one. A final remark about the assembly of this omnidirectional treadmill 1000 is that this embodiment is obviously missing the critical safety features which it would need for commercial viability. This embodiment is obviously a prototype, but further embodiments would make any dangerous pinch-points inaccessible, with the addition of padding or even a harness capable of providing safety in the event of a user falling over.

[0036] The final system of this described embodiment is the belt control system 600, which is used to control the motorized drive units 510 such that the treadmill belt 100 is moved to negate a user's attempted traversal movements and keep them centered on the treadmill deck 200. This capability requires a method of detecting which lateral direction a user is attempting to move; this embodiment's method of accomplishing that will hereafter be referred to as the lateral force detection system 610. The lateral force detection system 610 consists of a series of sensors which are each capable of directionally detecting the translational forces 630 which are imparted into the treadmill belt 100 by a user's movements. These sensors should be capable of detecting both the static and dynamic forces applied to the treadmill belt such that even small forces, which are incapable of overcoming the omnidirectional treadmill's internal or external resistances 640, are detectable. In this described embodiment, the drive electronics 512, which are mounted to the back of each electric motor 511, each have a built-in static/dynamic torque sensor 611 which can detect all static and dynamic translational forces applied to the treadmill belt 100 which apply a torque to the shaft of that electric motor 511 through its motor-driven omniwheel 520. This allows for millinewton-meter level torque measurement precision, though additional sensors could be added elsewhere for increased precision. With each static/dynamic torque sensor 611 only being oriented to measure translational forces which are in-line with the driven direction of that electric motor 511, the data from all of these sensors can be used in combination with the user's known mass to calculate the directional acceleration vector which would describe that user's lateral movement across the treadmill belt 100. All sensor data is utilized in the, closed loop, belt control system 600, where a PID controller 620 receives static/dynamic torque sensor 611 data and translates that into commands which cause the electric motors 511 in each motorized drive unit 510 to move in such a way as to minimize shaft torque. This results in horizontal movements 110 in the treadmill belt 100 which essentially negate the attempted traversal movements of a user, thereby keeping them centered on the treadmill deck 200.

[0037] Many modifications and other embodiments of the present disclosure will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the present disclosure is not to be limited to the specific embodiment disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.