Abstract:
Foot placement sensor and self-balancing vehicles having same. The foot placement sensor may be configured in or with a self-balancing transportation device that has a least a first foot platform. The sensor may include an emitter of electromagnetic radiation (or other suitable signal) that is propagated, at least in part, over a portion of the foot platform and a receptor positioned to receive this emission. Interruption of the emitted radiation at the receptor may indicate the presence of a user&#39;s foot at the platform. One suitable emission type is infrared light, among other suitable types. Various embodiments are disclosed including in two-wheel, one-wheel and paired-wheel self-balancing vehicles.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/279,166, filed Jan. 15, 2016, and having the same title and inventor as above. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to self-balancing personal transportation devices and, more specifically, to foot presence or foot position based activation of such devices. The present invention is particularly well suited for use in a two-wheel self-balancing devices that have independently movable wheels, though may be used in other devices, for example, but not limited to single wheel and single wheel-structure devices. 
       BACKGROUND OF THE INVENTION 
       [0003]    U.S. Pat. No. 8,738,278 (the &#39;278 patent) to Shane Chen, the inventor herein, discloses a Two-Wheel Self-Balancing Vehicle with Independently Movable Foot 
         [0004]    Placement Sections. This patent is hereby incorporated by reference as though disclosed in its entirety herein. 
         [0005]    Since the development and disclosure of the device of the &#39;278 patent, knock-off devices have been manufactured and widely marketed. In popular culture, these devices may be referred to as “hoverboards.” 
         [0006]    The devices are battery powered. In an effort to conserve power and to quickly stop the device when a rider dismounts (or falls off), the devices may include a foot sensor that is configured along with their associated control electronics to turn off self-balancing when a rider is no longer on the platform. This arrangement conserves power. 
         [0007]    One type of prior art foot sensor is a pressure (or weight based) sensor, detecting when a user is standing on the platform. These sensors are typically mounted to the surface of the foot platform and include an internally disposed movable member. When weight is applied to the sensors, the movable member is displaced such that it activates a transducer or breaks a light beam, etc., to generate a signal. Various pressure sensors are known in the art. 
         [0008]    The pressure sensors are disadvantageous in that they include a moving part and thus are more likely to fail. They are also disadvantageous in that, in the context of a self-balancing transportation device, they require sufficient pressure precisely delivered to the sensor. When (re)activating the device, this may necessitate a rider bending over and holding the device while attempting to apply pressure of sufficient force and direction to trip the sensor, or awkwardly hooking the device with one foot and trying to apply that pressure. 
         [0009]    Another type of sensor is a proximity sensor. Proximity sensors typically consist of an emitter and a co-housed detector. They emit electro-magnetic radiation and detect radiation that is reflected back. Infrared is a known type of electro-magnetic radiation, among others, used in proximity sensors. 
         [0010]    The infrared proximity sensors, however, are disadvantageous in that when shoes are worn that are not sufficiently reflective, for example, duller black shoes, there is insufficient reflection for the sensor to function properly. Thus, they may falsely indicate the absence of a rider and de-activate self-balancing with a dull, dark shoed rider is actually on the device. 
         [0011]    Hence, a need exists for a foot sensor arrangement for a self-balancing personal transportation device that has no or fewer moving parts, works regardless of the reflectivity of the rider&#39;s footwear, and/or that allows a user to activate self-balancing in an ergonomically-friendly manner, i.e., without a rider bending over or awkwardly trying to position the device for mounting, among other needs. 
       SUMMARY OF THE INVENTION 
       [0012]    Accordingly, it is an object of the present invention to provide a foot presence sensor for a self-balancing personal transportation device that overcomes the shortcomings of the prior art. 
         [0013]    It is another object of the present invention to provide a foot presence sensor for a self-balancing personal transportation device that incorporates such a foot placement sensor. 
         [0014]    It is also an object of the present invention to provide a foot presence sensor that propagates an emission over a portion of a foot platform and detects the emission with a detector spaced from the emitter. 
         [0015]    These and related objects of the present invention are achieved by use of a foot presence sensor and self-balancing personal transportation device having same as described herein. 
         [0016]    The attainment of the foregoing and related advantages and features of the invention should be more readily apparent to those skilled in the art, after review of the following more detailed description of the invention taken together with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a perspective view of a self-balancing personal transportation device having a foot presence sensor in accordance with the present invention. 
           [0018]      FIG. 2  is a bottom view of transportation device of  FIG. 1 . 
           [0019]      FIGS. 3-4  are upper right side and mid-right side perspective views (from the perspective of a rider), respectively, of a single-wheel structure, self-balancing transportation device having a foot presence sensor. 
           [0020]      FIG. 5  is a perspective view of a single wheel structure self-balancing personal transportation device having a foot presence sensor in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Referring to  FIG. 1 , is a perspective view of a self-balancing personal transportation device  10  having a foot presence sensor  50  in accordance with the present invention is shown.  FIG. 1  illustrates a device with two wheels (arranged laterally to the line of direction of travel). It should be recognized that the present invention may include or be practiced in devices that have a single wheel ( FIG. 3 ) or single wheel-structure ( FIG. 5 ) or other self-balancing devices. 
         [0022]    Device  10  may be similar to vehicle  100  of the &#39;278 patent. Device  10  may have a first and a second platform section  20 , 30 . Each platform section  20 , 30  may include a housing  16  formed of a top housing member  17  and a bottom housing member  18 . Each platform section  20 , 30  preferably has a foot contact surface  22 , 32 , respectively, on which a rider places his or her feet during use. A wheel  27 , 37  is preferably coupled to and associated with each platform section  20 , 30 , respectively, and a fender  28 , 38  may shield each wheel. Fenders  28 , 38  may include a side wall  29 , 39 , though only side wall  39  is visible from the perspective of  FIG. 1  (side wall  29  is arranged symmetrically with side wall  39  about a central vertical plane in the line of direction of travel of the device). 
         [0023]    The two platform sections are preferably movable rotationally with respect to one another to afford independent movement of the platform sections and independent driving and control of their respective wheels. It should be recognized, however, that the platform sections may be non-independently movable or movable other than by rotation, e.g., a flexible platform frame, etc., without departing from the present invention. 
         [0024]      FIG. 1  illustrates two foot presence sensors  50 , each associated with one of the foot platform sections. In the embodiment of  FIG. 1 , these sensors preferably include an emitter  51  and a receptor or detector  52  (receptor and detector are intended to be used interchangeably herein). Suitable emitters and receptors/detectors are known in the art. 
         [0025]    Emitter  51  may be positioned inwardly of foot contact surface  22 , 32  and receptor  52  is located outwardly of foot contact surface  22 , 32 , on fender wall  29 , 39 , respectively. 
         [0026]    In one embodiment, among others, emitter  51  may be an infrared (IR) LED that transmits a beam to its corresponding receptor. Infrared may be characterized as light, not in the visible spectrum, or more generally as electro-magnetic radiation. Various electro-magnetic radiation (and of different frequency) may be used by the foot presence sensors without departing from the present invention. 
         [0027]    The infrared signal from transmitter  51  is preferably modulated (by the control processor  73 , 83  of the respective platform section) to distinguish it from other IR sources. Modulation of IR or other electro-magnetic signals is known in the art. 
         [0028]    Emitter  51  preferably produces a substantially linear beam that originates adjacent and propagates over its corresponding foot contact surface. In  FIG. 1 , the beam diagonally traverses the air space immediately above the foot contact surface. “Over” is generally intended to mean adjacent and spaced from, i.e., above when the platform is horizontal and right side up, and/or such that a user standing on the foot platform would interrupt the beam with his or her foot or lower leg. 
         [0029]    It should be noted that the position of the emitter and receptor may be other than as shown in  FIG. 1  so long as the beam traverses air space above (i.e., over) the foot contact surface to detect the presence of a foot. The angle, placement, number and beam shape of the emitter and receptor may vary greatly without deviating from the present invention. For example, for each platform section, multiple receptors may be used to detect multiple beams or a “sector” emission or any other arrangement (i.e., shape) of emission from the emitter(s) to receptor(s) over the foot contact surfaces  22 , 32  may be utilized. 
         [0030]    Furthermore, the positions of the emitter and receptor may be reversed with the emitter being on the side wall  29 , 39  and the receptor on the foot platform. In yet another embodiment, one or more receptor pairs may be mounted on opposing side walls and project a beam across both foot platforms. In this manner, one emitter/receptor pair is sufficient to detect foot presence, yet having a foot presence sensor for each platform section individually provides more precise and efficient control. 
         [0031]    Referring to  FIG. 2 , a bottom view of transportation device  10  of  FIG. 1  is shown.  FIG. 2  provides a block diagram of some components within housing  16 . These may include motors  71 , 81 , batteries  72 , 82 , electronic control  73 , 83 , and position sensors (such as a gyroscopic sensor)  74 , 84 , respectively. The batteries power the motors which drive the respective wheels. While two electronic controls  73 , 83  are shown, one electronic control that controls both motors may be utilized. Similarly, a single battery powering both motors may be used. Sensor  74 , 84  provide position information for their respective platform sections  20 , 30 , respectively.  FIG. 2  also illustrates an on-off switch  12 . These components are generally known in the art, for example, as taught in the &#39;278 patent. The electronic control is preferably configured such that if at least one of the beams is interrupted, self-balancing is activated or if both are uninterrupted, self-balancing is de-activated. Note that there may be a pre-programmed or user set delay between detection of uninterruption and de-activation. 
         [0032]    The housing  16  may be formed of metal, sturdy plastic or other suitable material. The housing members  17 , 18  may be molded and incorporate strengthening reinforcements, and be shaped to receive and “nest” the internal components (discussed above). The bottom and top housing sections  17 , 18  are formed complementarily so that after the internal components are installed, the top housing section is fitted onto the bottom housing section and secured with screws or other fasteners.  FIG. 1  illustrates holes through which the fasteners are inserted. 
       In Use 
       [0033]    The present invention offers many advantages over prior art devices. One of them is in mounting the device. In prior art devices with pressure or weight based sensors, a user has to bend over and hold the device while mounting or awkwardly try to position the device with one foot and then step on. In the present invention, a user need only pass their foot through the “light” beam and the device springs to position. This may be done with an easy foot movement. 
         [0034]    In use, once on-off switch  12  is turned on, self-balancing is preferably activated. This activation may continue for a matter of time (without sensors  50  tripped), likely in the seconds range, before it “times out” and shuts off. There is a balance between ease of use and energy conservation. Similarly, when a ride dismounts, there may be a brief delay before de-activation, for example, to accommodate riders who are attempting to recover or doing stunts. Furthermore, the device is preferably configured so that self-balancing remains active so long as at least one foot is detected on a foot platform section. The amount of delay and whether that delay is set in manufacture or programmable by a user may vary without departing from the present invention. 
         [0035]    Referring to  FIGS. 3-4 , upper right side and mid-right side perspective views (from the perspective of a rider), respectively, of a single-wheel structure, self-balancing transportation device  110  having a foot presence sensor  150  are shown. Note that single wheel structure means that there may be one or more tires mounted to the rim, but if more than one, the tires have a common rim or rims that are fixedly joined to one another such that they have a common axis of rotation and rotate at the same speed, thus acting as a single wheel, yet with more than one tire. 
         [0036]    Device  110  may include a wheel  112 , having a rim and a tire  116 , drive motor(s)  161 , battery(ies)  170 , electronic control  180 , and a position sensor  182 , among other components. A housing  120  covers portions of wheel  112  and other components, some of which are shown in phantom line. 
         [0037]      FIG. 3  illustrates two “humps” or “protrusions”  121 , 131  and  122 , 132  per side (left and right side), with one protrusion  121 , 131  covering the drive motors and the other protrusion  122 , 132  covering the batteries. Between these two protrusions is a leg recess  123 , 133  that may contact, in a preferred embodiment, the inside of the lower leg of a user below or at the knee, during use. A foot platform  125  is located toward a bottom of the device, adjacent a lower portion of wheel  112 . The foot platform  125  has a heel region  126  and a ball region  128 . A similar foot platform is provided on the other side of the wheel for the rider&#39;s left foot (and is substantially symmetrically arranged). The leg recesses  123 , 133  are substantially aligned over their corresponding heel regions  126 , 136 , respectively. 
         [0038]      FIGS. 3-4  also illustrate a foot presence sensor  150  having an emitter  151  and a receptor or detector  152 . A foot presence sensors  150  is preferably provided for both feet (i.e., there is a similar arrangement on the left side of device  110 ). Sensor  150  and the emitter  151  and receptor or detector  152  preferably function in the same manner as sensor  50  and emitter  51  and receptor  52  discussed above. In  FIGS. 3-4 , the emitter  151  is coupled under protrusion  121  and projects rearwardly towards receptor  152  located above the rear of foot platform section  125  (which is essentially the foot contact surface as described with reference numerals  22 , 32  with reference to  FIG. 1 ). 
         [0039]    As with device  10  of  FIG. 1 , when a foot is detected by sensor  150  (beam broken), self-balancing is activated and when a foot is not detected, self-balancing is disabled. 
         [0040]    The emitter  151  and receptor  152  may be arrange other than as illustrated in  FIGS. 3-4  without deviating from the present invention. 
         [0041]    Referring to  FIG. 5 , a perspective view of a single wheel-structure self-balancing vehicle  210  having a foot presence sensor in accordance with the present invention is shown. Device  210  may have two fold out (or fixed, or other) foot platforms  220 , 230 , and two tires  216 , 217  mounted to a common rim or to coupled-position rims or the like. Foot presence sensors may be provided with each foot platform and may include an emitter  251  and a receptor/detector  252 . 
         [0042]    Appropriate electronic control, positions sensors, battery, drive motor, etc., are provided as discussed herein for devices  10  and  110 . 
         [0043]    While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention and the limits of the appended claims.