Abstract:
A device for adapting a manual wheelchair to drive with a powered wheel is disclosed. The device attached to the wheelchair provides means for raising the wheelchair front caster wheels and simultaneously having the powered wheel contact the driving surface. The disclosed device may be rotated so that the powered wheel lifts from the surface as the front caster wheels are lowered to contact the driving surface enabling manual operation of the wheelchair. The disclosed device includes a mechanism for steering the powered wheel, controls for varying the forward or backward speeds and braking. The device may be detached from the chair and is adaptable to fit a large variety of wheelchairs with capability for ergonomically adjusting the steering column for the comfort of the user. Optional human interface devices may be incorporated so the chair occupant may control speed and steering by operating a joystick, head array or other such devices.

Description:
Joy stick controls have been popular where direction and speed are provided by the position of a universal motion joy-stick. In the case of the disclosed apparatus, left or right joy-stick movement would control steering the wheel driver hub. Forward or back joy-stick movement would control the speed of the wheel driver hub in the forward or backward rotation. 
     Voice-controlled wheelchairs have also been proposed, but the variety and precision of the control they afforded has been less desirable. Furthermore, there has been a problem with commands being heard by the control system and the potential for the control system responding to a false command picked up from ambient noise, such as from the voices of people around the wheelchair. 
     There are other methods for controlling wheelchair movement and are well documented in the art. Those skilled in the art will be familiar with modular or integral control systems and, in addition to those systems discussed above, will have knowledge of controls using movements of the chin, head, finger, touch pads, wafer boards, proximity switches as well as remote radio controls and/or voice commands including interfaces with mobile devices or timers controlling usage. 
     Outdoor operation on soft ground and up and down grades, presents additional, challenging obstacles for both users of a hand propelled wheelchair and for those users unable to provide hand propulsion who depend on powered wheelchairs with electrical controls such as joy-stick controllers. 
     Most powered wheelchairs and powered scooters are heavy, complicated, expensive machines. They have small, fat tires and fairly complex joy stick-operated control systems. They generally include two electric motors that may be driven by one or more large lead-acid batteries. While intended for outdoor as well as indoor use, the machines are ill-suited for unpaved surfaces like grass and dirt. Nonetheless, powered wheelchairs and scooters have been a boon to the handicapped and elderly. 
     Scooters generally have a single motor that drives the wheels through a differential. While the costs and weight of a differential are about the same as an extra motor and gear reduction mechanism, the controls on the scooter are less complicated and the unit is generally more reliable than a two-motor wheelchair. Steering of the front wheel of the scooter is accomplished with a small handlebar. The shopping cart is the most popular type powered scooter and, while designed primarily for indoor use, it also sees limited outdoor service in transporting both the user and groceries across the store parking lot. These vehicles&#39; major drawbacks of cost, bulk and weight (generally in the range of 150 to 200 pounds), have prevented their widespread acceptance despite their obvious advantages. In contrast, the disclosed apparatus weights approximately twenty-five pounds. Convention powered chairs or scooters also require special measures in order to transport them. A serious drawback is that the motor drives the wheels through gearing which cannot be overdriven. Thus a drive failure, or a dead battery, can leave the 200 pound vehicle frozen in place with its wheels effectively locked and the user helplessly stranded. 
     Generally a special type van, or other vehicle providing a large door opening and specialized access equipment, is required to transport powered wheelchairs and powered scooters. The expensive vehicle is usually equipped with a power lift of some sort to enable loading and unloading of such a wheelchair. 
     The present invention is specifically directed for application to standard wheelchairs. Despite the maneuverability and transportability of these manual wheelchairs, powered wheelchairs are far more capable of handling grades, soft surfaces such as grass and off road conditions. There are other devices for converting manual wheelchairs to power, but none using the single powered wheel of the present invention. The present invention fulfills the need to enable light weight wheelchairs to be less expensively motorized and, if necessary, provide the option for joy-stick, head movement or other similar human interface devices for control without detracting from the appearance, maneuverability and transportability of the wheelchair. 
     The disclosed invention may be attached and detached from a standard chair. When detached the disclosed apparatus is readily transportable in the trunk of a compact automobile along with the chair. The disclosed apparatus including the electric battery providing motive power may be attached to a standard chair in a few minutes and when attached provides a simple method for elevating the front wheels of the wheelchair and preparing to drive forward, backward and steer. In the preferred embodiment of the disclosed invention, the drive mechanism consists of a wheel driver hub revealed in the U.S. Pat. No. 6,974,399 entitled, “Hub motor mechanism” and issued to Chiu-Hsiang Lo. This patent describes an electrically driven hub comprising an electrical motor and a planetary gear system connected to the motor. A first fixed shaft is connected to the stator of the electrical motor and a second fixed shaft is connected to a second end of the stator of the electrical motor. The first and second fixed shafts are connected to the vehicle frame. A one-way clutch is connected between a cover of the hub and the planetary gear system so that the hub is rotated when the planetary gear system is activated by the motor powered by a battery. In an alternative embodiment, the disclosed invention may utilize a wheel driven by an external motor. 
     The disclosed invention has the capability to elevate the driven wheel and lowering the front caster wheels of the wheelchair and, thus, the wheelchair may be operated in the manual mode when the apparatus is attached but with the drive wheel in the disengaged position. In this state, the wheelchair may still be easily hand propelled because of the disclosed invention&#39;s light weight and lack of bulk. When the wheel driver hub of the disclosed invention is engaged, the propelled wheelchair has excellent maneuverability and a top speed up to 10 miles per hour. Steering is accomplished in the preferred embodiment by turning the propelling wheel driver hub and is controlled by the user using a handlebar, or, alternatively using another means of control such as a joy-stick or other human interface device operating through servo-mechanisms. The turning radius of the wheelchair with the disclosed invention attached is approximately the same as the chair with the apparatus detached. Additional controls for speed and steering may be added for those users who are unable to operate the handlebars and speed controls manually. 
     OBJECTS OF THE INVENTION 
     A principal object of the invention is to provide an affordable attachment for a standard wheelchair which provides electrically powered propulsion. 
     Another object of the invention is to provide a novel propulsion system for powering a standard wheelchair that is easily attached to and detached from the wheelchair. 
     Another object of the invention is to provide a novel propulsion system that is lightweight, and easily transportable. 
     A feature of the invention resides in the arrangement for rapidly converting a manual wheelchair into a powered wheelchair. 
     Another feature of the invention resides in a motorized and steerable wheel driver hub that provides forward or reverse propulsion with steering accomplished with an attached handlebar, or less manual application such as a joy-stick, voice control or other non-manual means. 
     A still further feature of the invention resides in an adjustable cross bar for enabling the invention to be attached to wheel chairs with a range of dimensions and differing frame structures. 
     Another feature of the invention resides in the dual capabilities for powering the wheelchair when the steering column of the disclosed device is in the vertical position and the powered wheel contacts the driving surface with the wheelchair&#39;s front caster wheels elevated or rotating the steering column to elevate the driven wheel thereby lowering the front caster wheels and enabling manual operation of the wheelchair. 
     The disclosed invention features two telescoping adjustments of the steering column whereby different sections of the steering column may be secured at different lengths to ergonomically accommodate the user and to fit a particular wheelchair&#39;s dimensions. 
     Another feature of the disclosed invention resides in the capability of the steering column to be locked in a vertical position or driving mode so that the driven wheel contacts the driving surface and the front caster wheels are elevated off the driving surface. Alternatively, the steering column may be rotated with the steering mechanism pushed away from the user and the driven wheel rotated backward and thus elevated while the front caster wheels are lowered to contact the driving surface. 
     Yet another feature of the disclosed invention is that the top section of the steering column may be unlocked and rotated toward the user. 
     A further object of the disclosed invention is to provide the capability of modifying the preferred embodiment of the disclosed apparatus to provide the capability for controlling the driven movement by using any of the variety of human interface devices such as a joy-stick, sip and puff system or others. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects and features of the invention will be apparent upon reading the following description in conjunction with the drawings in which: 
         FIG. 1A  shows a prior art, manually operated wheelchair with typical lateral horizontal and vertical frame members on each side of the wheelchair, front caster wheels, battery mount and seat. 
         FIG. 1B  shows a perspective view of the disclosed apparatus with a wheel driver hub. 
         FIG. 1C  shows a perspective view of the disclosed apparatus mounted on a wheelchair. 
         FIG. 2A  shows a front view of the disclosed apparatus with a wheel driver hub. 
         FIG. 2B  shows a side view of the disclosed apparatus with a wheel driver hub. 
         FIG. 2C  shows a side view of the disclosed apparatus with an externally powered wheel. 
         FIG. 2D  is a back view of the disclosed apparatus with an externally powered wheel. 
         FIG. 3A  is a front view of the crossbar of the disclosed apparatus showing more detail of the first and second Tracking Plates affixed to the Central portion of the Cross Bar. 
         FIG. 3B  is a top view of the crossbar. 
         FIG. 3C  is a perspective view of a portion of the middle portion of the crossbar showing the first and second tracking plates, the pivot pin and the back tracking plate. 
         FIG. 3D  is a side view of the crossbar seen from the end presenting the first end clamp tightening screw. 
         FIG. 4A  shows a side view of the wheelchair. 
         FIG. 4B  is a side view of the wheelchair with the disclosed apparatus attached and the steering column of the apparatus rotated forward, the front caster wheels and in contact with the travel surface and the wheel driver hub elevated. 
         FIG. 4C  is a side view of the wheelchair with the disclosed apparatus attached to the wheelchair and with the whole steering column of the apparatus in the vertical position, the front caster wheels of the wheelchair elevated and the wheel driver hub in contact with the travel surface. 
         FIG. 5A  shows an expanded perspective view of the wheelchair with the first end clamp of the crossbar clamped on a lateral, horizontal frame member of the wheelchair. 
         FIG. 5B  shows a perspective view of the wheelchair with the first end clamp of the crossbar clamped on a lateral, vertical frame member of the wheelchair. 
         FIG. 6A  is a perspective view of the wheel driver hub, the wheel fork-steerer tube construct showing the header tube coaxially placed over the steerer tube and the bearing assembly at the lower end of the header tube, the U-shape slots at the ends of the wheel fork extensions to accept the axle of the wheel driver hub, and the bolts holding the wheel driver hub onto the branches of the wheel fork. 
         FIG. 6B  is a perspective view of the wheel driver hub fitting between and secured to the wheel forks, the steering neck, the steerer tube and the header tube with bearing assemblies inserted into the ends of the header tube. 
         FIGS. 6C , D, E and F provide more views of the combined steerer tube-wheel driver hub assembly where  FIG. 6C  is a top view of the steerer tube inside the header tube and the combination resting on the wheel fork neck;  FIG. 6D  is a perspective view of this combination;  FIG. 6D  is a front view of the combination additionally showing the nuts securing the axle of the wheel driver hub in place at the ends of the wheel fork extensions; and  FIG. 6F  is a side view of the combination. 
         FIG. 6G  is an exploded perspective view of the header tube descending on the steerer tube and meeting the elements of the lower bearing assembly contacting the wheel fork neck. 
         FIG. 6H  is an exploded perspective view of the upper end of the header tube ascending to the upper bearing assembly and contacting the clamp to secure the position of the header tube on the steerer tube. 
         FIG. 7A  is a perspective view of the header tube clamp assembly  60  inserted between the tracking plates with the clamp assembly affixed to the header tube and providing the pivotal connection enabling the rotation of the steering column. 
         FIG. 7B  is a front perspective view of a section of the crossbar showing the elements of the header tube clamp assembly. 
         FIG. 7C  is a rear perspective view of a section of the crossbar showing the back side of the header tube clamp assembly. 
         FIG. 7D  is an exploded view of elements of the header tube clamp assembly. 
         FIG. 7E  is a perspective view of the elements of the header tube clamp assembly used to move the a tracking pin so that it traverses the tracking grooves in the tracking plates. 
         FIG. 7F  is a perspective view of the middle section of the cross bar with the header tube clamp assembly pivotally connected to the middle section of the crossbar and the header tube directed through the cylindrical element of the header tube clamp assembly and showing the tracking pin positioned between the tracking plates to maintain the steering column in the vertical position. 
         FIG. 7G  is a perspective view of the assembly of  FIG. 7F  but with the steering column rotated and showing the tracking pin moved to facilitate the rotation. 
         FIG. 7H  is a perspective view of the header tube clamp assembly  60  shown in  FIGS. 7F and 7G  showing the tracking pin in transition from one locking position to another in the process of rotating the steering column. 
         FIG. 7I  is a perspective view from the rear of the cross bar showing elements of the header tube clamp assembly  60  and particularly the back tracking plate affixed to the crossbar between the tracking plates. 
         FIG. 7J  is a perspective view of the header tube clamp assembly showing the cut cylinder and the closing extension affixed to the front of the cut cylinder and the clamp handle pivotally affixed to the closing extension in the closed position. 
         FIG. 7K  is a perspective view of the header tube clamp assembly showing the cut cylinder and the closing extension affixed to the front of the cut cylinder and the clamp handle pivotally affixed to the closing extension in the open position. 
         FIG. 8A  is a perspective view of the upper tilting assembly in the closed position. 
         FIG. 8B  is a perspective view of the upper tilting assembly in the open position whereupon the upper portion of the steering column may rotate. 
         FIGS. 9A and 9B  are perspective views of the apparatus where  FIG. 9A  shows the crossbar at a low position on the header tube and  FIG. 9B  shows the crossbar elevated toward the top of the header tube. 
         FIGS. 9C and 9D  are perspective view of the apparatus where  FIG. 9C  shows the steering mechanism extension shaft almost completely lowered into the steering mechanism extension tube and  FIG. 9D  shows the steering mechanism extension shaft elevated in the steering mechanism extension tube. 
         FIGS. 10A , B, C, and D are multiple views of the disclosed apparatus where the upper tilt/pivot assembly is joined rotatably and telescopically to the top section of the steering column and the top section of the steering column is rotated in various positions toward the user of the wheel chair. 
         FIG. 11A  is a front view of the handlebar assembly of the preferred embodiment with the steering mechanism extension shaft with its top end orthogonally affixed to the center of the handlebar assembly descending coaxially into the steering mechanism extension tube which and with a clamp used to secure the steering mechanism extension shaft in the steering mechanism extension tube thus adjusting the length of this portion of the steering column. 
         FIG. 11B  is a perspective view of the handlebar assembly showing additionally the throttle adjoining the controller assembly, the battery power indicator as part of the controller assembly, the controller, the brake handle and brake platform, the steering mechanism extension shaft descending into the steering mechanism extension tube and the clamp securing this combination. Beltway 
         FIG. 12  is a view of the disclosed apparatus including the battery, the controller and electrical connections. 
         FIG. 13A  is a side view of the disclosed apparatus displaying the brake assembly and the brake cable controlling the brake calipers on the wheel driver hub. 
         FIG. 13B  is front view of the disclosed apparatus displaying the brake assembly and the brake cable controlling the brake calipers on the wheel driver hub. 
         FIG. 14  shows an alternative embodiment where the wheelchair with the disclosed apparatus attached is controlled by a human interface device such as a joy-stick. In this embodiment, the handlebars are replaced by a unit containing servo-mechanisms. The steering mechanism extension shaft extends downward from the servo-mechanism assembly. 
         FIG. 15  is a flow chart showing the steps in using a human interface device such as a joy-stick, sip and puff, voice-activated commands or other external means to control speed and direction of the motion of the wheelchair with the disclosed apparatus attached. 
     
    
    
     SUMMARY OF THE INVENTION 
     The disclosed invention comprises an attachable/detachable power drive apparatus that may be quickly and easily installed on a manually operable wheelchair to convert it into a motor driven wheelchair. The invention includes a steering mechanism, a steering column, a crossbar that may be attached to the frame of the wheelchair, a battery, a battery charge indicator, a motorized wheel, a control system, and a brake. The length of the steering column may be adjusted in two different ways. The crossbar of the disclosed apparatus is adjustable to adapt to a range of wheelchair dimensions. The steering column of the disclosed apparatus is pivotally connected to the crossbar and may rotate in a vertical plane. Once attached, the invention may be operated in the motor driven mode with the steering column locked in a vertical position so that the powered wheel is in contact with the travel surface and the front caster wheels of the wheelchair are elevated. When the steering column is rotated with the steering mechanism moving forward and downward and the powered wheel rotated backward and upward and thus disengaged from the travel surface, the front caster wheels of the wheelchair contact the travel surface so the wheelchair may be operated in the manual mode. The upper portion of the steering column telescopes to adjust the height of the steering mechanism. The lower portion of the steering column telescopes to adjust the length of the column below the crossbar to achieve the proper length so that the driven wheel contacts the driving surface and the front caster wheels are elevated. Lastly, a portion of the steering column may be unlocked so that the upper portion of the steering column may rotate back toward the user. 
     The disclosed apparatus is configured with a crossbar with clamps that attach to frame members on either side of the wheelchair as will be more fully described in the following. A steering column comprises steering and control means at the top of the steering column and culminates in a motor driven wheel at the bottom. The steering column is attached perpendicularly to the center of the crossbar with a fitting that permits the steering column to rotate between a position where it is vertical and the motor driven wheel contacts the driving surface and the front caster wheels are elevated and the wheelchair is operated in a powered mode. In a second position, the upper portion of the steering column is pushed forward, the motor driven wheel is rotated backward and upward and the front caster wheels contact the driving surface. In this configuration, the wheelchair may be operated in the manual mode. The disclosed apparatus has another feature wherein an upper portion of the steering column may be folded forward to enable easier access by the user of the wheelchair. 
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1A  shows a prior art, manually operated wheelchair  200  with typical lateral horizontal frame members  210  and  220 , vertical lateral frame members  230  and  240 , front caster wheels  250  and  260 , and seat  270 . Some of these wheelchairs are designed for portability, and generally include mechanisms that permit folding to facilitate storage in automobile trunks and the like. It will be appreciated that such wheelchairs are well known in the art and form no part of the present invention. 
       FIG. 1B  shows a perspective view of the disclosed apparatus  5 . The features and capabilities of the disclosed apparatus will be revealed in the following discussion. 
       FIG. 1C  shows a perspective view of the disclosed apparatus  5  mounted on the first  210  and second  220  lateral vertical frame members of the wheelchair  200 . Other features identified in  FIG. 1C  are the wheelchair&#39;s  200  first lateral horizontal frame member  230  and second lateral horizontal frame member  240 . Other wheelchair  200  features pictured are the first front caster wheel  250 , the second front caster wheel  260  and the seat  270 . 
       FIG. 2A  is a front view of the disclosed apparatus  5  including the crossbar  170  which enables attachment to frame members of the wheelchair, the battery  140  which may be placed in several different compartments attached to the wheelchair which are not shown and the controller  110  which is shown not yet placed on the apparatus. It will be clear to one skilled in the art that, given the flexibility afforded by the electrical leads, the battery and the controller may be placed in several places on the wheelchair or the apparatus. The battery is electrically connected through the controller  110  to the powered wheel  10 , which in the preferred embodiment is a wheel driver hub with an internal motor. In this figure and subsequent discussion, the steering column  29  comprises the elements of the apparatus beginning with the handlebar extension  98  (or other steering mechanism in an alternative embodiment as will be shown in a later figure) which descends from the steering mechanism assembly  100  which, in the preferred embodiment is a handlebar construct, and which joins with additional components and shall be further discussed in the following. The steering column continues and extends to the ends of the first wheel fork branch  22  and the second wheel fork branch  26 . 
       FIG. 2B  is a line drawing depicting a side view of the disclosed apparatus  5  shown in  FIG. 2A  further indicating the U-shape slot  24  in the first wheel branch fork  22 . The first end of the axle  12  of the powered wheel directed through the center of the wheel driver hub  10  is placed into the U-shaped slot  24  and held in place by the first nut  14 , shown in more detail in  FIGS. 6A , B, C, D, and E threading onto the end of the first end of the axle  12 . In an alternative embodiment, the wheel driver hub is replaced by a wheel driven by an external motor. In this instance, those skilled in the art will know that the axle  12  geometry and securing first and second nuts  14  and  16  will remain the same. The second end of the axle  12  and its securing nut  16  are not shown in  FIG. 2B  but are similarly shown in more detail in  FIG. 6B . C, D, and E. Other elements of the disclosed apparatus  5  are the crossbar  170 , the header tube clamp assembly  60  and the upper tilt assembly  80 . These latter elements will be more fully described in subsequent figures and discussion. 
       FIGS. 2C and 2D  show a side view and a back view of an alternative embodiment of the disclosed apparatus  5  where the wheel driver hub  10  is replaced by a wheel  8  driven by an external motor  9  attached to the lower portion of the steering column  29 . 
       FIG. 3A  is a front view of the crossbar assembly  170  comprising the end clamps  181  and  182  which can be affixed either to horizontal or vertical frame members of the wheelchair, the tightening means  185  and  186  comprising knurled knobs with threaded extensions penetrating through the end clamps  181  and  182  whereby the tightening means can close the end clamps  181  and  182  on the chosen wheelchair frame members, the central portion of the cross bar  180  into which fit extendably the first insertable inner tube  183  fitting into the first end  178  of the central portion of the cross bar  180  and the second insertable inner tube  184  fitting into the second end  179  of the central portion of the cross bar  180 , the first and second tightening means  187 , and  188  with similar construction as tightening means  181  and  182  and which when tightened against the inserts  178  and  179  stabilize the length of the crossbar extending between the chosen frame members on either side of the wheelchair, and the first and second tracking plates  189  and  190  affixed to the Central portion  180  of the Cross Bar  170 , the pivot pin  193 , the tilt tracking pin  66 , the back tracking plate  194  which is affixed between the tracking plates  189  and  190  will be additionally shown in subsequent figures. The tracking plates  189  and  190 , the pivot pin  193 , the tilt tracking pin  66  and the back tracking plate  194  form elements of the header tube clamp assembly  60  and will be shown in more detail in subsequent figures. 
       FIG. 3B  is a top view of the crossbar  170  showing the end clamps  181  and  182  which can be affixed either to horizontal or vertical frame members of the wheelchair, the tightening screws  185  and  186  which close the end clamps  181  and  182  on the chosen wheelchair frame members, the central portion of the cross bar  180  into which fit extendably the first insertable inner tube  183  fitting into the first end  178  of the central portion of the cross bar  180  and the second insertable inner tube  184  fitting into the second end  179  of the central portion of the cross bar  180 , the first and second tightening screws  187 , and  188  which when tightened against the inserts  178  and  179  stabilize the length of the crossbar extending between the chosen frame members on either side of the wheelchair, and the first and second tracking plates  189  and  190  affixed to the Central portion  180  of the Cross Bar  170 , the pivot pin  193 , the tilt tracking pin  66  the back tracking plate which is affixed between the tracking plates  189  and  190  will be shown in subsequent figures. The tracking plates  189  and  190 , the pivot pin  193 , the tilt tracking pin  66  and the back tracking plate form elements of the header tube clamp  60  shown in more detail in subsequent figures. 
       FIG. 3C  is a perspective view of the first and second tracking plates  189  and  190  affixed to the central portion of the crossbar  180 , the back tracking plate  194  affixed between the tracking plates  189  and  190 , the pivot pin  193  extending between the tracking plates  189  and  190 , the tilt tracking pin  66  extending between the first and second tracking grooves  191  and  192 . 
       FIG. 3D  is a side view from one end of the crossbar  170  depicting the first end clamp tightening means  185 , the first tightening means  187 , the first tracking plate  189  affixed to the central portion of the crossbar  180 , the first tracking groove  191  and the pivot pin  193 . 
       FIG. 4A  is a side view of the wheelchair  200  with the disclosed apparatus removed. The first lateral horizontal frame member  210  and the first front caster wheel  250  are indicated. All four wheels of the wheelchair are on the driving surface  1 . 
       FIG. 4B  is a side view of the wheelchair  200  with the disclosed apparatus  5  attached where the end clamps  185  and  186  of the crossbar  170  are attached to the horizontal frame members  210  and  220  (not shown) and the upper end of the apparatus  5  is rotated forward about the pivot pin in the header tube clamp assembly  60 . In this position, the wheel driver hub  10  of the preferred embodiment of the disclosed apparatus  5  is elevated and no longer in contact with the driving surface  1 . With the wheel driver hub  10  so elevated, the front caster wheels  250  and  260  (not shown) of the wheelchair  200  contact the driving surface  1  and the wheelchair may be operated in manual mode and propelled by the operator. 
       FIG. 4C  is a side view of the wheelchair  200  with the disclosed apparatus  5  attached where the end clamps  185  and  186  of the crossbar  170  are attached to the horizontal frame members  210  and  220  (not shown) and the upper end of the apparatus  5  is rotated back toward the wheelchair seat and the operator. In this mode, the wheel driver hub  10  contacts the driving surface  1  and the front caster wheels  250  and  260  are elevated above the driving surface  1 . This is accomplished by adjusting the length of the steering column  29  which will, with the other elements enabling this maneuver, be discussed and shown in subsequent figures. In this configuration, the wheelchair and attached apparatus may be operated in the powered mode. 
       FIG. 5A  is an expanded perspective view of a portion of the wheelchair  200  indicating the first horizontal frame member  210  with the end clamp  181  of the crossbar  170  affixed thereto. The first vertical frame member  230  is also shown. 
       FIG. 5B  is and expanded perspective view of a portion of the wheelchair  200  indicating the first vertical frame member  230  with the end clamp  181  of the crossbar  170  affixed thereto. 
       FIG. 6A  is a perspective view of the lower elements of the disclosed apparatus comprising the header tube  50  with the bottom bearing assembly  31  inserted into the bottom end of the header tube  50  descending to contact the wheel fork neck  21  of the wheel fork  20  and further comprising the wheel the first and second wheel fork branches  22  and  26 , the wheel driver hub  10  transected medially by the axle  12 , The first end of axle  12  is threadably connectable to the nut  14  The second end of the axle  12  similarly passes through the second U-shape notch  28  (not shown) located in the end of the second wheel fork branch  24  and is threadably connected to the second nut  16  (not shown). When the nuts  14  and  16  are threaded onto the first and second ends of the axle  12 , the wheel driver hub  10  is firmly affixed between the wheel fork branches  22  and  26 . The wheel driver electrical lead  18  extending from the first end of the axle  12 , passing through the first U-shape notch  24  in the end of the first wheel fork branch  22 , passing through the nut  14  and ending in the wheel driver electrical lead connector  19  will be illustrated in subsequent figures. 
       FIG. 6B  is a perspective view of the components presented in  FIG. 6A  showing more explicitly the wheel fork neck  21 , the first wheel fork branch  22 , the first U-shape notch  24 , the nut  14  binding the first end of the axle  12  of the wheel driver hub  10  or other powered wheel, the electrical lead  18  emanating from the first end of the axle  12 , the steerer tube  30  extending upward from the steerer neck  21  of the wheel fork  20 .  FIG. 6B  also shows the header tube  50  with the bearing assembly  31  inserted into the lower end of header tube  50  and the bearing assembly  35  inserted into the upper end of header tube  50 . The header tube  50  will be shown to be fit coaxially over the steerer tube  30 . 
       FIG. 6C  is a top view of the steerer neck over the wheel driver hub  10  or other powered wheel, and the securing nuts  14  and  16  threaded onto the first and second ends of axle  12 . The steerer tube  30  residing inside the header tube  50  can be seen on end. 
       FIG. 6D  is a perspective view of the lower section of the steering column showing the wheel driver hub  10  mounted between the branches  22  and  26  of the wheel fork  20 , the steerer tube  30  extending upward through the header tube  50  resting on the wheel fork neck  21 . At each end of the header tube there is a first and second bearing assembly  31  and  35 . 
       FIG. 6E  is a front view of the same features shown in  FIG. 6D . 
       FIG. 6F  is a side view of the same features shown in  FIG. 6D . 
       FIGS. 6G and 6H  show perspective views of the bearing assemblies  31  and  35  with bearing assembly  31  comprising a bearing race  32 , a plurality of ball bearings  33  contacting and moving on the bearing race  32  and a flanged bearing cup  34  with its flanged end fitting inside the lower end of header tube  50  and its wider end fitting over the bearing race  32  thus enclosing the ball bearings  33  in a circular track. The second and upper end of header tube  50  shown in  FIG. 6H  receives the second bearing assembly  35  shown in  FIG. 6H  and is identical to the first bearing assembly  31  and comprises bearing race  36 , bearings  37  and bearing cup  38  with the flanged end of cup  38  fitting into the second (top) end of header tube  50 . The ball bearings  33  shown in  FIGS. 6G and 37  shown in  FIG. 6H  contact the steerer tube  30  and provide a low friction feature so that the steerer tube  30  may rotate freely inside the header tube. Clamp  88  shown in  FIG. 6H  secures the position of the header tube  50  on the steerer tube  30 . The ball bearings  37  in the upper bearing assembly  35  serve not only to provide a low friction feature to facilitate rotation of the steerer tube but also facilitate rotation of the cylindrical clamp  88  adjoining the bearing race  36  so that the bearing  36  may rotate freely. In the same way, ball bearings  33  facilitate rotation of the steerer tube inside header tube. 
       FIG. 7A  is a perspective view of the header tube clamp assembly  60  inserted between the first and second tracking plates  189  and  190  (not shown) affixed to the center of the center piece of the crossbar  180 . This assembly  60  is slid over and affixed to the header tube  50  before the upper bearing assembly  35  (not shown in this figure is inserted into the top end of the header tube  50 . The header tube clamp assembly  60  is secured in place on the header tube  50  using the cut cylinder clamping structure  62  which is closed using the action of clamp handle  63  thereby securing the header tube clamp assembly  60  at a selected position on the header tube  50 . Once the clamp assembly  60  is secured in place, the upper bearing assembly  35  is inserted into the top of the header tube.  50 . The header tube clamp assembly  60  provides the pivotal connection shown in  FIGS. 4B and 4C  in combination with the tracking plates  189  and  190  extending from the central section of the crossbar  180 . The remainder of parts comprising the header tube clamp assembly  60  comprise the first tracking groove  191  located diagonally in the first tracking plate  189  and the second tracking groove parallel to the first tracking groove and located in the second tracking plate  190  (not shown), the pivot pin  64  which extends between the first and second tracking plates  189  and  190  around which the header tube clamp assembly  60  rotates when the tracking tilt pin  66  which extends between the tracking plates  189  and  190  is moved through the tracking grooves  191  and  192 .  FIG. 7A  also shows the bottom bearing assembly  31  resting on the wheel fork neck  21 . The order of assembly of these elements is that the bottom bearing assembly  31  is fitted into the bottom of the header tube  50 , the header tube  50  is placed over the steerer tube  30 , the header tube clamp assembly  60  is placed over the header tube  50  and affixed in place and the upper bearing assembly  35  is then fitted into the top of the header tube  50 . 
       FIG. 7B  is a front perspective view of the center section  180  of the crossbar  170  showing additional elements of the header tube clamp assembly  60 . In  FIG. 7B , the rear release platform  67  forms a portion of clamp assembly  60 . The rear release platform  67  extends orthogonally and upwards from the cylindrical portion  62  of the clamp assembly  60  and the central section of the crossbar section  180 . The rear release platform contacts the back tracking plate  194  (shown in  FIG. 7C ) which is affixed and contacts the center portion of the crossbar  180  and is located between the first and second tracking plates  189  and  190 . The release cable  70  extends downward through a groove in the rear release platform  67  and contacts and is affixed to the J-hook  72  which contacts the tilt tracking pin  66  which contacts the curved portion of the J-hook  72 . Vertical motion of the J-hook  72  lifts the tilt tracking pin  66  and enables the tilt tracking pin  66  to move along the tracking grooves  191  and  192  which further enables the rotation of the steering column  29  to assume the positions displayed in  FIGS. 4B and 4C . The tilt tracking pin  66  extends between both the tracking plates  189  and  190  and the tracking grooves  191  and  192 . The tracking grooves  191  and  192  are configured as arcs with deflected grooves at each end. The tilt tracking pin  66  resides in the deflections closest to the cross bar  170  when the steering column  29  is in the upright position with the wheel  10  in contact with the driving surface  1 . 
       FIG. 7C  is a perspective view of elements of the clamp assembly  60  showing the cut cylinder assembly  62  which when tightened around the header tube  50  secures the cut cylinder assembly  62  at the selected position, the tracking pin  66  able to traverse the tracking grooves  191  and  192 , the release cable  70 , the rear release platform  67 , the J-hook  72 , the release cable and handle  70  and the release guide  68  in which the J-hook slides. 
       FIG. 7D  is a more transparent perspective view of the elements of the clamp assembly  60  showing the same elements as  FIG. 7C  but showing more of the J-hook  72  contacting the tracking pin  66  and the tracking pin  66  extending across the assembly. 
       FIG. 7E  is an exploded and more transparent view of parts comprising the clamp assembly showing the parts displayed in  FIGS. 7C and 7D . 
       FIGS. 7F ,  7 G and  7 H illustrate the movement of the tilt pin  66  moving between the two positions where the steering column  29  is in the vertical position as in  FIG. 7F  and the inclined position shown in  FIG. 7G . When the tilt tracking pin  66  is lifted by the release cable  70  and the top of the steering column  29  is pushed forward, the tilt tracking pin  66  slides along the tracking grooves  191  and  192  until the tilt tracking pin  66  comes to rest at the ends of the deflections furthest from the cross bar  170 . In this state, the steering column is rotated so that the wheel  10  is elevated and the front caster wheels  250  and  260  contact the driving surface  1 . The steering column  29  may be returned to the vertical position by reversing the process, namely, releasing the tilt tracking pin and pulling the top of the steering column toward the occupant of the wheelchair. The deflections in the tracking grooves  191  and  192  insure that the steering column is locked and remains in the selected position. 
       FIG. 7H  illustrates the tilt pin  66  in mid traverse in the tracking grooves  191  and  192 . 
       FIG. 7I  is a rear perspective view of the mid-section  180  of the crossbar  170  showing the back side of the header tube clamp assembly  60 . In this view, the rear release platform  67  is shown in contact with the back tracking plate  194  which is affixed and contacts the center portion of the crossbar  180  and is located between the first and second tracking plates  189  and  190 . The release cable  70  is seen descending through the groove in the rear release platform  67 . Portions of the J-hook  72  and the release guide  68  can be seen through the oval opening in the center of the rear release platform  67 . 
       FIG. 7J  is a perspective view of the header tube clamp assembly  60  showing the cut cylinder  62  and the closing extension  61  affixed to the front of the cut cylinder  61  and the clamp handle  63  pivotally affixed to the closing extension  61  where the clamp handle is in the closed position resulting in closure of the cut cylinder  62  and further resulting in securing the header tube clamp assembly  60  at a selected position on the header tube  50 . 
       FIG. 7K  is a perspective view of the header tube clamp assembly  60  showing the cut cylinder  62  and the closing extension  61  affixed to the front of the cut cylinder  61  and the clamp handle  63  pivotally affixed to the closing extension  61  where the clamp handle  63  is in the open position thereby opening the gap in the closing extension  61  and subsequently opening the gap in the cut cylinder  62  allowing the header tube clamp assembly  60  to slide along the header tube  50  and assume different position. 
       FIG. 8A  is a perspective view of the upper tilting assembly  80  in the closed position. This assembly comprises an upper platform  91  with a cylindrical portion  94  extending upward and orthogonally from the surface of the upper platform  91 , a lower platform  81  with a similar cylindrical portion  87  extending downward and orthogonally from the lower platform  81  and a control knob  86  connected to a T-pin  84  which is shown in  FIG. 8B . The upper tilt pivot pin  90  acting as an effective hinge and which traverses from side to side of the lower platform  81  through accommodating openings in the bottom platform  81 . The upper platform  91  is also shown in  FIG. 8B . The cylindrical portion  94  meets and inserts into the bottom of the steering mechanism extension tube  95  shown in  FIGS. 9A , B, C, and D. The steering mechanism extension tube  95  is secured coaxially on the cylindrical portion  94  by a cylindrical clamp  93  also shown in  FIGS. 9A , B, C, and D. 
       FIG. 8B  is a perspective view of the upper tilting assembly  80  in the open position displaying the T-shape clamping pin  84  whose cross bar traverses openings in the bottom platform  81  and whose shaft controls rotation of the clamping pin  84  to meet the U-shape opening  85  in the upper platform  91  thus closing and locking the lower and upper platforms  81  and  91  of the tilting assembly  80 . The knurled control knob  86  is threadably connected to the shaft of the T-pin  84  and may be tightened against the upper platform  91  to secure the assembly  80  in the closed position or may be unscrewed and loosened so that the T-pin  84  may swing and allow opening of the lower  81  and upper  91  platforms. 
       FIGS. 9A and 9B  illustrate movement of the header clamp assembly  60  along the header tube  50 .  FIG. 9A  shows the header clamp assembly  60  and the crossbar  170  in a low position secured to a lower portion of the header tube  50 .  FIG. 9B  shows the header clamp assembly  60  and the crossbar  170  elevated toward the top of the header tube  50 . Other elements of the disclosed apparatus are provided for reference. 
       FIGS. 9C and 9D  illustrate movement of the steering mechanism extension shaft  98  in the steering mechanism extension tube  95  to vary the length of the steering column.  FIG. 9C  shows the steering mechanism extension shaft  98  almost fully inserted into the extension tube  95 . The position of the extension shaft is secured by the cylindrical clamp  94 . 
       FIGS. 10A , B, C, and D is a set of side views of the disclosed apparatus  5  showing the steering column  29  in various positions and where the upper tilt/pivot assembly  80  is joined rotatably and extendably to the steering extension shaft  98  which is the top section of the steering column, the tilt assembly is opened using the knurled knob  86  controlling the rotation of the clamping lever which rotates the clamping pin  84  to release the top section of the upper tilt assembly  91  thus enabling rotation of the handlebar assembly  100  and the handlebar extension  98  to the various positions displayed. The clamp  88  securing the bottom platform  81  of upper tilt assembly  80  to the top of the steerer tube  30  and the clamp  94  securing the handlebar extension  98  to the upper platform  91  of the upper tilt assembly  80  are also shown in the sequence in  FIG. 9 . 
       FIG. 11A  is a view of the steering mechanism assembly  100  which, in the preferred embodiment, comprises first and second handlebars  102  and  104 . The steering mechanism extension shaft  98  is shown with its top end orthogonally affixed to the center of steering mechanism assembly  100  and with a cylindrical clamp  94  used to secure the steering extension shaft  98  in position on the steering extension tube  95 . The first  102  and second  104  handlebars are shown with the brake platform  106  and brake handle  108  shown attached to the second handlebar  104 . The controller  110  (shown in  FIG. 12 ) is affixed to the handlebar extension shaft  98  and electrically connected with lead  122  to the control assembly  112  comprising the throttle  113 , the forward/reverse toggle button  114  (shown in  FIG. 11B ) and battery life meter  124  (shown in  FIG. 11B ). 
       FIG. 11B  is a perspective view of the steering mechanism  100 , which as show in this figure is the preferred embodiment, the handlebars  102  and  104 , the forward/reverse toggle button  114 , the control assembly  112 , the throttle lever  113  and the battery life meter  124 . For reference, the steering mechanism extension shaft  98 , the cylindrical clamp  94  and the steering mechanism extension tube  95  are also shown. 
       FIG. 12  is a schematic view of the disclosed apparatus showing the battery  140 , the electrical lead from the battery  140  to the controller  110  which is shown separate from the steering mechanism extension shaft. It will be apparent to those skilled in the art that the controller may be affixed to the steering mechanism and the battery may be located in various positions on the wheelchair. Additionally, the electrical lead  120  from the battery  140  to the controller  110 , the electrical lead  122  from the controller  110  to the motion control assembly  111  (throttle/meter/motion toggle button), the electrical lead  123  from the brake through the controller  110  and thence to the wheel driver  114  hub  10  to initiate electrical braking are also shown. In the preferred embodiment, the electrical power to drive the wheel driver hub is carried by electrical lead  130  which connects to electrical lead  18  which projects from the end of the wheel driver hub&#39;s  10  axle  12 . 
       FIGS. 13A and 13B  are a side view and front view of an alternative embodiment of the disclosed apparatus  5  displaying a mechanical brake  108 , and a brake cable  116  controlling a brake caliper assembly  115  further controlling a first and second brake caliper  118  and  119  on the wheel driver hub  10 . Those skilled in the art will recognize that the mechanical braking system may be substituted for or added to the electrical braking system previously described. Alternatively, the mechanical braking system may be utilized in the alternative embodiment utilizing a wheel driven by an external motor as shown in  FIGS. 14A and 14B . 
       FIG. 14  shows an alternative embodiment where the wheelchair with the disclosed apparatus  5  attached is controlled by a joy-stick  154  electrically connected by lead  152  to a plurality of servo-mechanisms  150  controlling direction and speed. The joy-stick  154  received power from the battery  140  via lead  156 . 
       FIG. 15  is a flow chart  300  schematically illustrating an electronic control system operable in accordance with the disclosed invention  5  with controlling commands opening with a reset of the logical construct  310  and further comprising a stop command for braking  320 , steering direction further comprising forward  330  or backward  340  speeds and right turns  350  or left turns  360  of the wheel driver hub  10  or powered wheel  8 . The control structure further comprises capacity for recognizing repeatable commands  370  and commands not recognized  380 . If a command is not recognized, the logic proceeds to the reset command  310 . The system illustrated includes the capability of stopping movement  380  if a command is not recognized. The flow chart  300  indicates the steps in generating commands using a human interface device such as a joy-stick, sip and puff, voice-activated commands or other external means to control speed and direction of the motion of the wheelchair  200 . 
     The control system  300  interfaces with a controller  110  operated in conjunction with a command generator such as a joy-stick or other command generating device. The controller  110  in this case operates using commands from the command generator and operates the servo-mechanisms that control the direction of the wheel driver hub  10  or the powered wheel  8  and the forward or reverse generated. The controller  110  can be any device suitable for controlling the wheelchair. In general, any device capable of controlling the transfer of data to and from a number of nodes where such nodes emanate from the command generating device will suffice.