Abstract:
A balancing vehicle that supports a rider on a support such as a seat in a such a manner as to allow the position of the center of gravity of the vehicle to be varied by motion of the support. Motion of the support additionally provides for control of a drive that propels the vehicle in a manner responsive to the position of the center of gravity. The vehicle is thus capable of control by leaning of a seated rider.

Description:
This application is a continuation in part application of copending U.S. application Ser. No. 09/325,976, filed Jun. 4, 1999, which is a continuation in part of U.S. application Ser. No. 08/479,901, filed Jun. 7, 1995, now issued as U.S. Pat. No. 5,975,225, which is a continuation in part of U.S. application Ser. No. 08/384,705, filed Feb. 3, 1995, now issued as U.S. Pat. No. 5,971,091. 
    
    
     TECHNICAL FIELD 
     The present invention pertains to a balancing personal vehicle having a support for a human subject, the support being pivotable in order to allow the subject to be supported at a desired angle with respect to ground contacting elements of the vehicle. 
     BACKGROUND OF THE INVENTION 
     Personal vehicles may be self-propelled and user-guidable, and, further, may entail stabilization in one or both of the fore-aft or left-right planes, such as whey no more than two wheels are in ground contact at a time. Vehicles of this sort may be operated in a mode in which motion of the vehicle, including acceleration (both linear and turning), is controlled partially or entirely by leaning of the vehicle as caused by a subject riding the vehicle. Several such vehicles are described in U.S. Pat. No. 5,971,091, issued Oct. 26, 1999, which is incorporated herein by reference. 
     Such balancing vehicles may lack static stability. Referring, for example, to FIG. 1A, wherein a prior art personal transporter is shown and designated generally by numeral  18 , a subject  10  stands on a support platform  12  and holds a grip  14  on a handle  16  attached to the platform  12 , so that the vehicle  18  of this embodiment may be operated in a manner analogous to a scooter. A control loop may be provided so that leaning of the subject results in the application of torque to wheel  20  about axle  22  thereby causing an acceleration of the vehicle. Vehicle  18 , however, is statically unstable, and, absent operation of the control loop to maintain dynamic stability, subject  10  will no longer be supported in a standing position and will fall from platform  12 . Another prior art balancing vehicle is shown in FIG.  1 B and designated generally by numeral  24 . Personal vehicle  24  shares the characteristics of vehicle  12  of FIG. 1A, namely a support platform  12  for supporting subject  10  and grip  14  on handle  16  attached to platform  12 , so that the vehicle  18  of this embodiment may also be operated in a manner analogous to a scooter. FIG. 2 shows that while vehicle  24  may have clusters  26  each having a plurality of wheels  28 , vehicle  24  remains statically unstable and, absent operation of a control loop to maintain dynamic stability, subject  10  will no longer be supported in a standing position and may fall from platform  12 . 
     SUMMARY OF THE INVENTION 
     In accordance with a preferred embodiment of the invention, there is provided a device for transporting a human subject over a surface. The device has a platform defining a fore-aft plane that supports a payload including the human subject. The device also has a ground-contacting module that includes a ground-contacting member movably coupled to the platform. The platform and the ground-contacting module are components of an assembly, and the position of the center of gravity of the assembly is defined with respect to the ground-contacting member. The device also has a support for supporting the subject, where the support is coupled to the platform in such as manner as to permit variation in the fore-aft plane of the position of the center of gravity. Furthermore, the device has a drive, coupled to the ground contacting module, for delivering power to the ground-contacting module in a manner responsive to the position of the center of gravity. 
     In accordance with alternate embodiments of the present invention, the support includes a seat. The support may be coupled to the platform at a pivot oriented to allow motion of the support about an axis substantially transverse to the fore-aft plane. The device may have a handle, affixed to the platform, having a grip at approximately waist height of the subject, so that the device may be operated in a manner analogous to a scooter. The ground-contacting module may be characterized by a region of contact with the ground and the support may have an articulated member, biased for supporting a portion of the weight of the subject, and the support may have a region of local stability substantially above the region of contact with the ground of the ground-contacting module. 
     In accordance with a further embodiment of the invention, there is provided a device for carrying a user, wherein the device has a platform and a user support having a position defined with respect to the platform and coupled to the platform in such a manner that the user may vary the position of the support with respect to the platform in the course of normal operation of the device. The device also has a motorized drive that propels the platform over an underlying surface through motion of at least one ground-contacting member and a controller, coupled to the motorized drive, for governing the operation of the motorized drive at least in response to the position of the user support. 
     In accordance with yet a further embodiment of the invention there is provided a device for conveying a seated user. The device has a platform for supporting a payload including the seated user, a ground-contacting module mounted to the platform that propels the platform with respect to an underlying surface, and a drive, coupled to the ground-contacting module, for delivering power to the ground-contacting module in a manner controlled solely by leaning of the user. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be more readily understood by reference to the following description, taken with the accompanying drawings, in which: 
     FIG. 1A is a side view of a prior art dynamically balancing vehicle of the type in which an embodiment of the invention may be advantageously employed; 
     FIG. 1B is a side view of a further prior art dynamically balancing vehicle of the type in which an embodiment of the invention may be advantageously employed; 
     FIG. 2 is a side view of a dynamically balancing vehicle having an articulated pivotable support in accordance with an embodiment of the invention; 
     FIG. 3 is a side view of the dynamically balancing vehicle of FIG. 2 showing the articulated pivotable support in a partially folded configuration; and 
     FIG. 4A is a side view of a dynamically balancing vehicle showing an articulated pivotable support in a further embodiment of the present invention; 
     FIG. 4B is a further side view of the embodiment of FIG. 4A showing two positions of the pivotable support; 
     FIG. 5A is a side view of a pivotable support having a central equilibrium position in accordance with a further embodiment of the present invention; and 
     FIG. 5B is a further side view of the embodiment of FIG. 5A showing detail of a cam-follower arrangement. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIG. 1A, prior art balancing vehicle  18  does not provide a seat for the subject  10  using the vehicle. The subject stands on a platform  12  and holds a grip  14  on handle  16  attached to platform  12 , so that the vehicle of this embodiment may be operated in a manner analogous to a scooter. The pitch of the vehicle may be sensed and compensated for in the control loop, so that if the subject leans forward, the vehicle will move forward, and similarly, leaning in other directions may cause corresponding motion of the vehicle. Accordingly, a forward lean will cause forward movement; a backward lean will cause backward movement. Appropriate force transducers may be provided to sense leftward and rightward leaning and related controls provided to cause left and right turning as a result of the sensed leaning. The leaning may also be detected using proximity sensors. Similarly, the vehicle of this embodiment may be equipped with a foot- (or force-) actuated switch to activate the vehicle, in such a manner that the switch is closed so as to power the vehicle automatically when the subject stands on the platform  12 . 
     Referring now to FIG. 2, a personal vehicle  30  is shown of the type in which pitch of the vehicle may be sensed and compensated for by application of torque to one or more wheel  32  (or other ground-contacting members) by operation of a control loop (not shown) and wheel actuator (not shown), so that if subject  10  leans forward, the vehicle is caused to move forward. As described in U.S. Pat. No. 5,971,091 at col. 5, lines 24 to 33, which is incorporated above by reference, a drive  531  delivers power to the ground-contacting members. It to be understood that platform  12  is not necessarily coupled directly to wheel  32 . Tilting of the vehicle is not necessarily canceled during ordinary operation of the vehicle, so that sustained motion and sustained acceleration may be achieved. In accordance with an embodiment of the present invention, a seat  34  is provided for supporting a portion of the weight of subject  10 . Subject  10  may still vary the position of his center of gravity, and the position of the center of gravity  36  of the combination of vehicle  30  and subject  10  while seat  34  continues to support a portion of the weight of the subject by virtue of the pivotability of seat  34  with respect to platform  12 . 
     It is to be understood that within the scope of the present invention, as described herein and as claimed in any appended claims, wheel  32  may rotate about a single axle, or, alternatively, about an axis that may vary in orientation, in the manner of a uniball. 
     Seat  34  may be coupled to platform  12  by any of a variety of mechanisms. In accordance with a preferred embodiment of the present invention, seat  34  is coupled to platform  12  via link  38 , itself pivotally coupled to platform  12 , and coupled to seat  34  at knee joint  40 . The articulated support comprising seat  34  and link  38  may be biased by a spring arrangement (not shown) or its equivalent so as to counter the weight of the subject. FIG. 3 shows seat  34  depressed at knee joint  40  with respect to link  38 . Additionally, pivot  42  is shown coupling link  38  to support platform  12  in a manner as to constrain link  38  to fore-aft motion about an axis substantially transverse to the fore-aft plane. The spring arrangement (not shown) may include any means, such as a coil spring or a gas spring, known for biasing the support mechanism for supporting some fraction of the weight of the subject. Additionally, mechanisms known in the art for providing for translation of seat  34  in a fore-aft direction for shifting the weight of subject  10  with respect to ground-contacting member  32  are within the scope of the present invention. 
     An alternative to the articulating folding seat of the embodiment of FIG. 3 is described with reference to FIG. 4A. A balancing personal vehicle  44  is shown in which seat  34  may be pivoted with respect to support platform  12  by means of a seat support mechanism designated generally by numeral  46 . Seat support  46  has two substantially linear members  48  which pivot in about pivots  50  through which linear members  48  are coupled to platform  12 . Linear members  48  are coupled to seat  34  at pivots  52 . A subject seated on seat  34  may shift her weight, and thereby the center of gravity of the combination of vehicle and subject, by moving seat  34  in a fore-aft direction. FIG. 4B shows the articulating folding seat of FIG. 4A in two positions: the position designated  54  places the center of gravity of the vehicle, including the rider, substantially above the region of contact of the ground-contacting member  20  (shown in FIG. 4A) with the ground. Seat  34  may also be folded up toward handle  16  as in the position designated by numeral  56 . In the embodiment shown in FIGS. 4A and 4B, seat  34  is highest, and thus possesses the greatest potential energy, in central position  54 . 
     Referring now to FIG. 5A, in accordance with other embodiments of the present invention, stability is provided by ensuring that the central position of the seated user, substantially above axle  22 , is a stable position, i.e., a position characterized by a local minimum of potential energy. Thus, with respect to the central position designated by numeral  54 , seat  34  is displaced further from platform  12 , and thus higher above level ground, as seat  34  is moved by virtue of the rider moving in either a forward direction  60  or an aft direction  62 . In accordance with the embodiment depicted in FIG. 5A, seat  34  is supported by a substantially trilateral arrangement  64  of links. Arm  66  pivots about a pivot point  68  fixed with respect to platform  12 , while link  70  couples arm  66  to seat  34 . Link  72 , substantially parallel to link  70 , supports seat  34  in a substantially horizontal orientation in its central position  54 . The third side of trilateral arrangement  64  is formed by link  74 . Link  74 , as shown in greater detail in FIG. 5B, may be a rigid member or a suspension member, as shown, containing a gas spring  76  which serves to cushion seat  34  with respect to vibration transmitted from the road surface through platform  12 . Link  74  is coupled to cam follower  78  which rides on cam surface  80  in such a manner as to provide a well  82  of stability at the center of motion of seat  34 . If seat  34  moves fore or aft, cam follower  78  is driven up cam  80 , thereby increasing the height of seat  34  relative to platform  12  relative to its position of stability at the center. This reduces the effort required of the rider to maintain a centered body position, thereby advantageously allowing the rider to maintain a more relaxed position and momentarily to remove his/her hands from the handlebar. 
     It is to be understood that other mechanical configurations providing for seat  34  to rise as seat  34  is moved either forward or aft of its central position  54  wherein the center of gravity of the vehicle and rider is substantially over the region of contact of the vehicle with the ground are within the scope of the present invention as claimed in the appended claims. 
     The described embodiments of the invention are intended to be merely exemplary and numerous variations and modifications will be apparent to those skilled in the art. All such variations and modifications are intended to be within the scope of the present invention as defined in the appended claims.