Abstract:
The stair-climbing apparatus has a series of articulating wheel sets extending below the platform. All of the wheel sets are vertically adjustable to negotiate stairways and similar changes of elevation. The lead wheel set is fixed longitudinally relative to the platform, while following wheel sets are longitudinally adjustable to adjust for the pitch or slope of different stairways. The apparatus uses sensors (e.g., mechanical, infrared, ultrasonic, etc.) to detect the presence of the stair risers and their height, control of the assembly being accomplished by a control circuit on board the machine. The wheel sets are raised and lowered independently of one another by pantograph mechanisms extending between the platform and the wheel sets. The horizontally adjustable wheel sets are positioned by a longitudinally disposed rack on the platform.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of my prior application Ser. No. 12/987,855, filed Jan. 10, 2011, now pending. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to powered devices for ascending and descending elevations, and particularly to a stair-climbing apparatus capable of free operation (i.e., not secured to another structure) on a flight of stairs or the like. 
     2. Description of the Related Art 
     The need for powered mechanical assistance for persons that have occasion to ascend or descend elevations has been known for a considerable period of time. This is particularly true for the elderly or infirm who have need to travel between floors of a multiple story building. The need also arises when transporting large and/or heavy articles between floors in a multiple story building, e.g., large office machines, such as console copiers, office or other furniture, etc. 
     Accordingly, elevators were developed well over one hundred years ago, and escalators were developed somewhat later. However, elevators and escalators require that the building structure provide for such devices, or the building structure must be modified extensively after completion in order to accommodate such lift devices. 
     As a result, various devices have been developed in the past for negotiating stairways and the like. Some of these devices are permanently installed along or on stairways to travel up and down the stairway. Often, these permanently installed machines also required modification of the building structure for their installation. Still other portable devices have been developed as well. Most, if not all, such devices require that the stairs have a constant pitch or slope in order for the device to function. If the stairs have a different pitch or slope between landings or between stories, most such devices are incapable of proceeding beyond the first flight of stairs. 
     Thus, a stair-climbing apparatus solving the aforementioned problems is desired. 
     SUMMARY OF THE INVENTION 
     The stair-climbing apparatus includes a wheeled undercarriage having a platform and three sets of vertically adjustable wheel pairs extending below the platform. Two of the three sets are also horizontally adjustable beneath the platform. The apparatus uses conventional electrical power to drive the wheels in order to advance the device to and onto the stairs. The various wheel pairs adjust vertically so that the platform remains horizontal at all times, the wheel pairs adjusting sequentially as required to negotiate the stairs. While the leading wheel pair or assembly is fixed at the forward end of the apparatus, i.e., it has no horizontal adjustment relative to the platform, the other two wheel pairs adjust forward and rearward beneath the platform in order to adjust for the difference in height between individual steps and to adjust for different pitches or slopes of stairways. The horizontal and vertical adjustment of the wheel pairs beneath the platform is controlled by proximity sensors, which detect the risers of the stair treads and adjust the wheel pairs accordingly. The proximity sensors may be of any conventional type, e.g., mechanical, infrared, ultrasonic, etc. A microcomputer or microcontroller receives the proximity signals and commands vertical and/or horizontal adjustment of the wheel pairs accordingly. 
     Vertical adjustment of the three sets of wheels is accomplished by a pantograph mechanism for each wheel set. Horizontal adjustment of the second and third wheel sets is accomplished by a track mechanism extending along the length of the platform, each of the second and third wheel sets having its own independent drive for horizontal adjustment. The wheels are provided with conventional electric or other drive means and brake means. The drive means may also serve as the brake means, depending upon the mechanism(s) incorporated. 
     These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of a stair-climbing apparatus according to the present invention, illustrating a first exemplary configuration. 
         FIG. 1B  is a perspective view of the stair-climbing apparatus of  FIG. 1 , illustrating an alternative configuration. 
         FIGS. 2A ,  2 B,  2 C,  2 D,  2 E,  2 F,  2 G,  2 H,  2 I,  2 J,  2 K,  2 L,  2 M,  2 N,  2 O,  2 P,  2 Q,  2 R,  2 S,  2 T,  2 U,  2 V,  2 W,  2 X,  2 Y and  2 Z are right side elevation views illustrating successive steps in the process involved as the stair-climbing apparatus of  FIG. 1A  ascends a flight of steps or stairs. 
         FIG. 3  is a block diagram of an exemplary control circuit for a stair-climbing apparatus according to the present invention 
     
    
    
     Similar reference characters denote corresponding features consistently throughout the attached drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The stair-climbing apparatus is a stand-alone machine, i.e., it has no attachment to the stairway structure upon which it operates, nor does the stairway structure require any modification(s) to accommodate the operation of the stair-climbing device. The apparatus is capable of negotiating stairways having different slopes and pitches of risers and treads, even along the same continuous stairway. 
       FIGS. 1A and 1B  of the drawings provide perspective views of the stair-climbing apparatus  10 .  FIG. 1A  illustrates the apparatus  10  with all of its wheel trucks extended, and  FIG. 1B  shows the exemplary retraction or raising of the first wheel truck and repositioning of the second end truck, as explained further below. The apparatus  10  comprises a platform  12  having a series of wheel carriages and wheel trucks adjustably extending below the platform. The carriages and trucks are controlled by appropriate conventional sensors and an on-board computerized system to adjust their positions as required to negotiate a flight of stairs. 
     The platform  12  has a first end  14 , i.e., which is the leading end of the apparatus  10  when negotiating a flight of stairs, a medial portion  16 , and an opposite second or trailing end portion  18 . The platform  12  has a width  20  that is preferably somewhat narrower than a conventional stairway. A plurality of wheel carriages is installed directly beneath the platform  12 . While any practicable number of such carriages may be provided, the three carriages  22   a ,  22   b , and  22   c  of the exemplary stair-climbing apparatus  10  is considered to be optimum. However, it will be seen that additional carriages (and their wheel truck assemblies, discussed further below) may be provided by using the same mechanism as provided for the three carriages illustrated and described herein. 
     The first end wheel carriage  22   a  is immovably affixed beneath the platform  12 , i.e., the first end carriage does not translate or move relative to the platform. However, the medial wheel carriage  22   b  and the second end portion wheel carriage  22   c  translate horizontally and longitudinally beneath the platform  12  when the apparatus  10  is in operation, as described further below. The longitudinal positioning of the two wheel carriages  22   b  and  22   c  is by means of an elongate rack  24  extending along the longitudinal axis of the platform  12  from a point near the first end  14  of the platform and a point on the second end portion  18  of the platform  12 . The medial wheel carriage  22   b  has a medial drive mechanism  26   b  extending therefrom and engaging the rack  24 , and the second end portion wheel carriage  22   c  has a substantially identical second end portion drive mechanism  26   c  engaging the rack  24 . The drive mechanisms  26   b  and  26   c  may comprise electric motors affixed to extensions of the respective carriages, each motor driving a pinion that, in turn, engages a track extending along the rack  24 . The rack  24  may also include guide rails to hold the drive mechanisms  26   b ,  26   c  and their respective wheel carriages  22   b ,  22   c  in proper alignment as they adjust longitudinally along the rack  24 . 
     In  FIG. 1A , it will be seen that the medial drive mechanism  26   b , and thus its medial wheel carriage  22   b , is positioned generally medially along the rack  24 , and the second end portion drive mechanism  26   c  and its corresponding second end portion wheel carriage  22   c  is positioned near the extreme second or rearward end of the rack  24  and platform  12 . In  FIG. 1B , the central or medial drive mechanism  26   b  and its wheel carriage  22   b  are in the same positions as shown in  FIG. 1A . However, the second end portion drive mechanism  26   c  has been actuated to move toward the opposite first end  14  of the platform  12 , thus reducing the distance between the second end portion drive mechanism  26   c  and its carriage  22   c  and the medial drive mechanism  26   b  and its carriage  22   b . The relative spacing between the wheel trucks and their wheels, discussed below, is adjusted accordingly. 
     Each of the wheel carriages  22   a ,  22   b , and  22   c  has a wheel truck  28   a ,  28   b , and  28   c , respectively, adjustably extending beneath the corresponding carriage. The wheel trucks  28   a  through  28   c  are substantially identical to one another, each of the trucks  28   a ,  28 , b , and  28   c  having a first end  30  and opposite second end  32  defining a span  34  substantially equal to the width  20  of the platform  12 . A first wheel  36  extends from the first end  30  of each of the wheel trucks  28   a  through  28   c , and a second wheel  38  extends from the opposite second end  32  of each truck. The wheels  36  and  38  are driven by conventional means, i.e., electric motors powered by an on-board electrical storage battery, the drive motors being contained in their respective wheel trucks or in the hubs of the wheels. Such drive means is well known and conventional, and may be incorporated into the stair-climbing apparatus  10 . 
     Each of the wheel trucks is adjusted vertically relative to the platform  12  by a corresponding pantograph linkage  40   a ,  40   b , and  40   c  extending between the wheel truck and its corresponding wheel carriage. The three pantograph linkages  40   a ,  40   b , and  40   c  are substantially identical to one another. Each linkage  40   a ,  40   b ,  40   c  comprises a first arm  42  and a laterally opposite second arm  44 , each of the arms  42 ,  44  having an upper or wheel carriage attachment end  46 ,  48  and an opposite lower or wheel truck attachment end  50 ,  52 . The upper ends  46 ,  48  of the two arms  42 ,  44  are pivotally attached to the corresponding lateral ends of their respective wheel carriages  22   a  through  22   c , and the opposite lower ends  50 ,  52  of the arms  42 ,  44  translate laterally along the corresponding wheel truck  28   a  through  28   c.    
     Each wheel truck  28   a  through  28   c  has a first track  54  and a parallel second track  56  extending laterally across the truck. The lower end  50  of the first arm  42  travels laterally along the first track  54 , and the lower end  52  of the opposite second arm  44  travels laterally along the second track  56  in each wheel truck  28   a  through  28   c . The lower ends  50 ,  52  of the two arms  42 ,  44  travel in opposite directions to one another and towards the respective opposite ends  32  and  30  of each wheel truck  28   a  through  28   c  as the wheel truck is lowered relative to the platform  12 . The lower ends  50 ,  52  of the two arms  42 ,  44  cross or pass one another at the midpoints of their respective tracks  54  and  56 , when the respective wheel truck has been raised somewhat from its fully extended position, as shown with respect to the wheel carriage  22   a  at the lead end  14  of the apparatus  10  in  FIG. 1B . The drive for this articulating arm system is accomplished by a motor  58  located on or in each wheel truck  28   a  through  28   c . The drive system may comprise conventional roller chains, toothed belts, worm drives, etc., as desired. 
       FIG. 3  is a block diagram of an exemplary control circuit for the stair-climbing apparatus  10 . The stair-climbing apparatus  10  includes proximity sensors  80  to sense when the apparatus approaches stair treads. The proximity sensors  80  also may also have the capability to sense the height of the stair risers, or the height sensors may be discrete devices that are generically included within the term “proximity sensors” in the present application. Such sensors are well known in the field of robotics. The apparatus  10  includes a control circuit  70  having a microcontroller  75  or microprocessor programmed to receive signals from the proximity sensors  80  and raise or lower the wheel trucks  28   a ,  28   b , and  28   c  or drive the wheels forward by control signals to the motors  58 , and to move the wheel carriages  22   b  and  22   c  translationally forward and rearward by control signals to the drive mechanisms  26   b  and  26   c . Again, such control circuits  70  are well own in the robotics art and need not be described further. 
       FIGS. 2A through 2Z  are schematic side elevation views showing a progression of operations of the apparatus  10  as it negotiates a flight of steps or stairs. In  FIG. 2A , the apparatus  10  is shown in its completely collapsed configuration, i.e., all of the support arms of the pantograph assemblies or linkages  40   a ,  40   b , and  40   c  (shown in varying states of extension and retraction in  FIGS. 2B through 2Z ) have been retracted to lower the platform  12  to its lowest state. The pantograph assemblies  40   a ,  40   b , and  40   c  do not need to be fully collapsed as the device is still approaching the first step S 1  of the stairway S, but complete retraction of all of the pantograph linkages provides more compact storage and a lower center of gravity for the device. 
     The riser of the first step S 1  is sensed by on-board detection means, e.g., infrared or other electromagnetic frequency means, ultrasonic detection, mechanical sensors, etc. The stair-climbing apparatus  10  includes means for detecting both horizontal proximity and the height of the risers of the stair steps. Such sensors are well known in the art, and need not be described further. As the first riser is sensed, the on-board computer or microcontroller system actuates the three pantograph linkage drive motors  58  of the three wheel trucks  28   a ,  28   b , and  28   c , causing the linkages  40   a ,  40   b , and  40   c  to extend generally as shown in  FIG. 2B  of the drawings. 
     It will be seen that the first wheel truck  28   a  cannot remain retracted or partially extended to clear the height of the riser of the first step S 1 , as the only support for the apparatus  10  would be by means of the two rearwardly located wheel trucks  28   b  and  28   c , which would cause the device to tip forward. Accordingly, the second wheel truck  28   b  is translated forward by moving its wheel carriage  22   b  forward along the rack  24 . The resulting configuration is generally as shown in  FIG. 2C . 
     Once this has been accomplished, the first or forward wheel truck  28   a  may be raised to clear the riser of the first step S 1 , generally as shown in  FIG. 2D . The apparatus  10  then senses that the forward truck  28   a  is no longer blocked by close proximity of the riser of the first step S 1 , and actuates the drive wheels  38  of the medial and/or second end wheel trucks  28   b  and  28   c  to move the apparatus  10  forward, thereby placing the wheels  38  of the first wheel truck  28   a  atop the tread of the first step S 1 , as shown in  FIG. 2E . 
     At this point, the on-board sensor system senses the proximity of the riser of the first step S 1  immediately in front of the second or medial wheel truck  28   b , and directs the medial pantograph linkage  40   b  to lift the medial wheel truck  28   b  to the level of the first end wheel truck  28   a  to clear the riser of the first step S, generally as shown in  FIG. 2F . Once this has been accomplished, the system applies motive power to the wheels of the first end and/or second end wheel trucks  28   a  and  28   c  (the wheels of the intermediate truck  28   b  are not in contact with a surface at this point) to drive the apparatus  10  forward, thereby placing the wheels of both the first end truck and medial truck  28   a  and  28   b  atop the first step S 1 , generally as shown in  FIG. 2G  of the drawings. 
     When this has been accomplished, the first end wheel truck  28   a  is again lifted by actuating its pantograph mechanism  40   a  in readiness for placement of its wheels atop the second step S 2 , generally as shown in  FIG. 2H . The apparatus  10  is once again driven forward, i.e., in the direction of the rising stairway S, resulting in the wheels of the first end truck  28   a  resting atop the second step S 2  and the wheels of the medial truck  28   b  resting atop the first step S 1  adjacent the second step riser, generally as shown in  FIG. 2I  of the drawings. 
     It will be noted that at this point there is sufficient horizontal room for the first wheel truck  28   a  to advance until it reaches the riser of the third step S 3 . However, the medial wheel truck  28   b  is abutting the riser of the second step S 2 , so no further forward progress may be made until the medial wheel truck  28   b  is lifted. This is shown in  FIG. 2J  of the drawings. Once this has been accomplished the apparatus  10  is once more driven forward until the wheels of both the first end wheel truck  28   a  and the medial wheel truck  28   b  are resting atop the second step S 2 , generally as shown in  FIG. 2K . 
     This general process is repeated, as shown in  FIGS. 2L and 2M , so that the first end wheel truck  28   a  is raised in preparation for placement atop the third step S 3  ( FIG. 2L ), and the apparatus is driven forward to place the wheels of the first end wheel truck  28   a  atop the third step S 3  while the medial wheel truck  28   b  abuts the riser of the third step S 3 . However, at this point it will be noted that the second end wheel truck  28   c  is abutting the riser of the first step S 1 . Thus, the stair-climbing apparatus  10  cannot advance further up the stairway S, regardless of the height of the medial wheels and wheel truck  28   b . Should the pitch or slope of the stairway S be somewhat different than that illustrated, the operating system of the apparatus  10  can adjust the fore and aft position of the second end portion wheel carriage  22   c , and thus the fore and aft position of the second end portion wheel truck  28   c  as required. 
     When the above procedure has been carried out as necessary, the medial wheel truck  28   b  is moved rearward by actuating its carriage drive  26   b  (shown in  FIGS. 1A and 1B ), as shown in  FIG. 2N  of the drawings. The medial pantograph linkage  40   b  is then extended to lower its medial wheel truck  28   b , thereby once again placing the wheels of the medial truck  28   b  atop the first step S 1  as shown in  FIG. 2O  of the drawings. 
     The rearward or second end support provided by repositioning the medial wheel truck  28   b  adjacent the second end portion truck  28   c  allows the second end truck  28   c  to be lifted as shown in  FIG. 2P . At this point the apparatus  10  is driven forward once again, positioning the second end portion wheel truck  28   c  and its wheels atop the first step S 1  immediately behind the medial wheel truck  28   b , generally as shown in  FIG. 2Q  of the drawings. 
     The process continues by lifting the medial wheel truck  28   b  in preparation for translating it forwardly, as shown in  FIG. 2R . It will be noted that due to the first end truck  28   a  and the second end truck  28   c  being separated in height by only two steps, it is not necessary to extend the second end pantograph linkage  40   c  to its full height. The first end pantograph is completely retracted at this point, as is the medial pantograph. This raises the medial wheel truck  28   b  and its wheels to the same elevation as the first or forward end wheel truck and wheels  28   a  to allow the medial truck  28   b  to move forward to rest upon the third step S 3  immediately behind the first end truck  28   a , as illustrated in  FIG. 2S . 
     At this point, the apparatus  10  must lift the first end wheel truck  28   a  once again in preparation for placing it atop the fourth step S 4 . However, the pantograph linkages of the first end truck  28   a  and the medial wheel truck  28   b  are retracted to their maximum extent, i.e., the first end and medial trucks  28   a  and  28   b  are immediately adjacent their respective carriages  22   a  and  22   b  and cannot be raised further. Accordingly, all of the pantograph linkages  40   a ,  40   b , and  40   c  are extended to provide sufficient room for the subsequent retraction of the first end wheel truck  28   a , generally as shown in  FIG. 2T , in preparation for another move forward up the steps S. (It will be seen that the control system may be programmed to hold the first or forward end wheel truck  28   a  in a completely retracted state rather than extending it as shown in  FIG. 2T , if so desired. The medial wheel truck  28   b  and second end portion wheel truck  28   c  provide sufficient support at this point.) In any event, the coordinated extension and retraction of the various pantograph linkages  40   a ,  40   b , and  40   c  as the apparatus  10  negotiates the stairway S assures that the platform  12  always remains level throughout the entire operation. 
     Once the platform  12  has been lifted, as shown in  FIG. 2T , the first or forward end wheel truck  28   a  is lifted once again (if it was not held in its lifted state during the operation described above in the discussion of  FIG. 2T ) to clear the fourth step S 4 , as illustrated in  FIG. 2U  of the drawings. The proximity sensor system of the device determines that there is some distance between each of the wheel trucks  28   a ,  28   b , and  28   c  and the corresponding risers of the steps S 5 , S 4 , and S 2 , and signals the drive means to move the apparatus  10  forward to the position shown in  FIG. 2V  of the drawings. 
     At this point, the medial wheel carriage  22   b  is translated rearward, i.e., toward the second end portion carriage  22   c , to position it over the second step S 2  as shown in  FIG. 2W . The medial wheel truck  28   b  is then lowered by extending its pantograph linkage  40   b  to place the wheels  36  and  38  of the truck  28   b  at rest on the second step S 2 , as shown in  FIG. 2X . This allows the rearward or second end portion wheel truck  28   c  to be raised to clear the riser of the second step S 2 , as shown in  FIG. 2Y . The horizontal clearance between the first and medial wheel trucks  28   a ,  28   b  and the risers of the respective steps S 5  and S 3  allow the stair-climbing apparatus  10  to advance toward those steps and to position the second end portion wheel truck  28   c  on the second step S 2 , as shown in  FIG. 2Z . 
     It will be seen that the above-described process may continue up the flight of stairs S to the extent necessary to reach the top of the stair or some other point along the stairway, as desired. The process would continue with the medial wheel truck  28   a  retracting and moving forward as shown in  FIGS. 2R and 2S , the platform  12  then being raised, as shown in  FIG. 2T . The process would continue generally as shown in  FIGS. 2U through 2Z , repeating the operation illustrated in  FIGS. 2R through 2Z  as necessary until reaching the destination on the stairway S. 
     While the operation has been described above as being a series of finite, sequential steps, it will be seen that the control system may be programmed to actuate the various operations in a fairly rapid and fluid sequence, allowing the stair-climbing apparatus to move smoothly and reasonably rapidly up a flight of stairs. It should also be noted that while only a description of the sequential moves involved in traveling up a flight of stairs has been provided herein, it is but a trivial matter to reverse the operation to allow the apparatus to travel down such a flight of stairs. 
     It will be seen that while the present discussion is directed to the use of the device on a fixed, stationary stairway, the stair-climbing apparatus may also be adaptable for use on a moving escalator by appropriate programming of the control system to account for the movement of the escalator steps at the bottom and top of the escalator. Such operations will of course depend upon the capability of the device to make positional adjustments to the wheel trucks sufficiently rapidly to accommodate the lifting action of the escalator steps at the bottom of the escalator, and the leveling of the steps at the top. 
     The stair-climbing apparatus  10  may be adapted to carry or lift virtually any practicable article up (or down) a flight of stairs. The platform  12  may be equipped with cargo tiedowns to secure various pieces of equipment thereto, e.g., large, heavy, and/or bulky office equipment such as console copiers, desks, and the like, or large appliances such as refrigerators, air conditioning units, stoves, etc. In addition, it will be seen that appropriate means for securing a wheelchair or the like to the platform may be provided, allowing the physically handicapped to reach different floors or levels in a building structure where no other means is available to them. 
     It is to be understood that the present invention is not limited to the embodiment described above, but encompasses any and all embodiments within the scope of the following claims.