Abstract:
An easily and quickly reconfigurable robot chassis with at least a pair of forward shafts and a pair of rearward shafts. A wheel is attachable to and removable from each drive shaft. A sprocket is also attachable to and removable from each shaft. A first pair of tracks each extend around opposing forward sprockets and rearward sprockets. A pair of forward track extenders are each removeably attachable to the chassis and each include a forward idler sprocket. A second pair of longer tracks each extend around opposing rearward sprockets, the forward sprockets, and forward idler sprockets. A pair of rearward track extenders are each removeably attachable to the chassis and each include a rearward idler sprocket. A third pair of still longer tracks each extend around opposing rearward idler sprockets, rearward sprockets, forward sprockets, and forward idler sprockets.

Description:
RELATED APPLICATIONS 
       [0001]    This application hereby claims the benefit of and priority to U.S. Provisional Application Ser. No. 61/125,372, filed on Apr. 24, 2008 under 35 U.S.C. §§119, 120, 363, 365, and 37 C.F.R. §1.55 and §1.78, incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The subject invention relates to robots and mobile vehicles. 
       BACKGROUND OF THE INVENTION 
       [0003]    There are numerous robots with specialized tracks configured to climb stairs and traverse obstacles. See, for example, U.S. Pat. No. 6,668,951 incorporated herein by this reference. 
         [0004]    Wheeled robots are also popular. The robots provided by Automatika, Inc. (Pittsburg, Pa.) and Foster-Miller, Inc. (Waltham, Mass.) are examples. The applicant&#39;s “Dragon Runner” robot, for example, includes four driven wheels. 
         [0005]    There are circumstances where it would be beneficial if a wheeled robot could be converted permanently or even just temporarily into a robot with tracks making the robot not only more terrainable, but also capable of climbing onto and over obstacles, including climbing and descending stairs. No known conversion system exists. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    It is therefore an object of this invention to provide a method of converting a wheeled robot into a track driven robot. 
         [0007]    It is a further object of this invention to provide a conversion system for converting a wheeled robot to a track driven robot. 
         [0008]    The subject invention results from the realization that, in one embodiment, a wheeled robot can be made more versatile if the wheels are easily replaced by track sprockets, that easily added forward track extenders allow the track robot to more easily traverse curbs and other obstacles, and that easily added rearward track extenders along with the forward track extenders allow the robot to more easily climb stairs. 
         [0009]    This subject invention features a reconfigurable robot comprising a chassis with at least a pair of forward shafts and a pair of rearward shafts. A wheel is attachable to and removable from each shaft. A sprocket is also attachable to and removable from each shaft. One set of tracks are each configured to extend around a forward sprocket and a rearward sprocket. In one preferred embodiment, a pair of forward track extenders are each removeably attachable to the chassis and each include a forward idler sprocket. A second pair of tracks are each configured to extend around a rearward sprocket, a forward sprocket, and a forward idler sprocket. A pair of rearward track extenders may also be provided, each removeably attachable to the chassis and each include a rearward idler sprocket. A third pair of tracks are each configured to extend around a rearward idler sprocket, a rearward sprocket, a forward sprocket, and a forward idler sprocket. 
         [0010]    In one preferred embodiment, all the shafts are driven. A forward pair of removable sprocket adapters and a rearward pair of removable sprocket adapters may be provided. Each sprocket adapter typically includes a threaded portion and the robot further including a threaded nut securing a track extender to the threaded portion of the sprocket adapter. The sprocket adapters and the track extenders may include features locking the desired angle of the track extenders. The forward track extenders preferably extend at an angle upwardly or downwardly from the chassis and, typically, both the forward and rearward track extenders extend substantially beyond the robot chassis. In one design, the track extenders all include a tensioning mechanism. The wheels and the sprockets are typically each removeably locked to their respective shafts via a hex portion on each shaft, a hex orifice in each wheel and sprocket, and a clip secured through an orifice through each drive shaft. 
         [0011]    The subject invention also features a reconfigurable robot comprising a chassis with at least a pair of forward shafts and a pair of rearward shafts; a wheel attachable to and removable from each forward shaft; a wheel attachable to and removable from each rearward shaft; a forward sprocket attachable to and removable from each forward shaft; a rearward sprocket each attachable to and removable from each rearward shaft; and a first pair of tracks each configured to extend around a forward sprocket and a rearward sprocket. 
         [0012]    One reconfigurable robot includes a forward sprocket attachable to and removable from each forward shaft; a rearward sprocket attachable to and removable from each rearward shaft; a first pair of tracks each configured to extend around a forward sprocket and a rearward sprocket; a pair of forward track extenders each removeably attachable to the chassis and each including a forward idler sprocket; and a second pair of tracks each configured to extend around a rearward sprocket, a forward sprocket, and a forward idler sprocket. Wheels, each attachable to and removable from a shaft, may also be supplied and used. A pair of rearward track extenders each removeably attachable to the chassis and each including a rearward idler sprocket may also be supplied and used along with a third pair of tracks each configured to extend around a rearward idler sprocket, a rearward sprocket, a forward sprocket, and a forward idler sprocket. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0013]    Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which: 
           [0014]      FIG. 1  is a schematic three-dimensional front view showing an example of a robot in accordance with the subject invention in a wheeled configuration; 
           [0015]      FIG. 2  is a schematic three-dimensional front view showing the robot of  FIG. 1  with tracks in an “off-road” configuration; 
           [0016]      FIG. 3  is a schematic three-dimensional front view of the robot shown in  FIGS. 1 and 2  with front track extenders installed in a “curb-climb” configuration; 
           [0017]      FIG. 4  is a schematic three-dimensional side view of the robot shown in  FIGS. 1-3  with both front and rear track extenders installed in a “stair-climb” configuration; 
           [0018]      FIG. 5  is a schematic three-dimensional view showing the primary components associated with installing a wheel on a drive shaft in accordance with the subject invention; 
           [0019]      FIGS. 6A-6F  are schematic three-dimensional views depicting the primary steps associated with installing wheels on the drive shafts on the robot of  FIG. 1 ; 
           [0020]      FIGS. 7A-7F  are schematic three-dimensional side views showing the primary steps associated with installing track extender adapters on the robot chassis of  FIG. 1  in accordance with the subject invention; 
           [0021]      FIGS. 8A-8P  are schematic three-dimensional views showing the primary steps associated with installing sprockets on the robot chassis; 
           [0022]      FIGS. 9A-9L  are schematic three-dimensional views showing the primary steps associated with installing front track extenders on the robot chassis; 
           [0023]      FIGS. 10A-10J  are schematic three-dimensional views showing the primary steps associated with installing both front and rear track extenders on the robot chassis; and 
           [0024]      FIGS. 11-12  are schematic side views of a track extender in accordance with the subject invention with an integral track tensioning mechanism. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    Aside from the preferred embodiment or embodiments disclosed below, this invention is capable of other embodiments and of being practiced or being carried out in various ways. Thus, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. If only one embodiment is described herein, the claims hereof are not to be limited to that embodiment. Moreover, the claims hereof are not to be read restrictively unless there is clear and convincing evidence manifesting a certain exclusion, restriction, or disclaimer. 
         [0026]      FIG. 1  shows a modified version of a prior art “Dragon Runner” robot  10  with chassis  12 , four wheels  14   a - 14   d , camera  18 , digital radio  22  (for radio control of the robot), and antennas  24   a  and  24   b . Other subsystems for the robot are possible including a turret and arm assembly and the like. See U.S. patent application Ser. No. 12/317,131 filed Dec. 18, 2008 and U.S. patent application Ser. No. 12/288,943 filed on Oct. 24, 2008 incorporated herein by this reference. 
         [0027]    In accordance with the preferred embodiment of the subject invention, wheels  14   a - 14   d  are all driven and yet easily attached to and removable from their respective drive shafts. When the wheels are removed, sprockets  70   a - 70   d  can be added resulting in the robot shown in  FIG. 2  with tracks  30   a  and  30   b . When front track extenders  90   a - 90   b  are added together with longer tracks  30   a ′ and  30   b ′,  FIG. 3 , the result is a robot better able to traverse curbs and other obstacles. When rear track extenders  92   a  are added together with still longer tracks  30   a  ″ and  30   b ″,  FIG. 4 , the result is a robot better able to climb stairs and stair-like obstacles. Preferably all the wheels and sprockets are driven but in other designs only the rear or forward wheels may be driven. The subject invention also applies to vehicles with more than four shafts. 
         [0028]      FIG. 5  shows one typically driven shaft  40   a  extending from chassis  12 , wheel adapter  42  secured to chassis  12 , wheel  14   a , spacer  44 , and clip  46 . In  FIG. 6A , hex-shaped driveshaft portion  41   a  is aligned with wheel hub hex opening  50 . Other means for positively engaging the wheels on their respective drive shafts are possible. In  FIG. 6B , wheel  14   a  is slid onto shaft  40   a . In  FIG. 6C , spacer  44  is slid onto the shaft and in  FIG. 6D , clip  46  is aligned with and then inserted,  FIG. 6E , into an orifice in hex shaft  40   a . In a similar fashion, wheels  14   b ,  14   c  and  14   d ,  FIG. 6F  can be installed on robot chassis  12 . Wheel removal involves performing these same steps in the reverse order. The result is wheels which are easy to install and remove without the use of tools. 
         [0029]    When tracks instead of wheels are desired, wheel adapter  42 ,  FIG. 7A  is removed as shown in  FIG. 7B  by removing the four screws securing wheel adapter  42  to chassis  12 . In  FIG. 7C , track hub adapter  60  with four screw holes is located and pushed onto the drive shaft and its screw holes are aligned with the screw holes in the chassis,  FIG. 7D .  FIG. 7D  also shows hex portion  41  a of shaft  40   a , threaded portion  61  of adapter  60 , and orifice  33  in shaft  40   a . Adapter  60  also includes features  63  used to positively lock a track extender in place at a desired angle. In  FIG. 7E , the screws are inserted through track hub adapter  60  and tightened onto robot chassis  12 . The same procedure is repeated for all the remaining axel hubs as shown in  FIG. 7F . Note that the wheels also work with track hub adapter  60 . Thus, one option is to have track hub adapter  60  always installed. 
         [0030]    In  FIG. 8A , sprocket  70   a  and clip  72   a  are located and then sprocket  70   a ,  FIG. 8B  is slid onto the drive shaft exposing the drive shaft hole. In  FIG. 8C , pin clip  72   a  is aligned with the shaft hole and then pushed through the hole into the locked setting,  FIG. 8D . In  FIG. 8E , the vehicle is turned onto its side with sprocket  70   a  facing upwards. Track  30   a ,  FIG. 8F  is located and wrapped around sprocket  70   a . In  FIG. 8G , the sprocket teeth are engaged in the center of track tread  30   a . In  FIG. 8H , track  30   a  is pinched in the center to elongate it along the free shaft end  76  of the chassis. A second sprocket assembly  70   b ,  FIG. 8I  is then aligned with the center of track  30   a  and the sprocket teeth are engaged into the center tread holes between the tread guides. In  FIG. 8J , the rear drive shaft is aligned with the sprocket  70   b  assembly hole and the sprocket is pushed onto the shaft and fully seated when the hole in the shaft is visible,  FIG. 8K . The shaft may have to be adjusted or wiggled so that the hexagonal hole in the hub of the sprocket assembly lines up and fully seats onto the hexagonal drive shaft,  FIG. 8L . In  FIG. 8M , hair pin clip  72   b  is aligned with the hole in the drive shaft and pushed through the hole,  FIG. 8N . Track  30   a ,  FIG. 8O  is now installed. By flipping the chassis onto the completed track side, the other track  30   b  can be installed in a similar fashion resulting in the configuration shown in  FIG. 8P . 
         [0031]    To install the front track extenders as shown in  FIG. 3 , rear sprocket  70   b ,  FIG. 9A  is installed and front track extender  90   a  with idler sprocket  92   a  is located,  FIG. 9B . Extender  90   a ,  FIG. 9C  is slid over the hub and aligned at the steep angle shown. Track  30   a ′,  FIG. 9D  is slid over extender sprocket  92   a  and rear sprocket  70   b . Again, the sprocket teeth should be aligned in the middle row of the tread holes and straddle the tread guides running along the inside center of the tread. In  FIG. 9E , extender  90   a  is rotated towards the front to tighten track  30   a ′. Extender  90   a  is preferably aligned at an upward angle of 18° with respect to the horizontal as shown in  FIG. 9E . In  FIG. 9F , the extender is pressed fully onto the hub adapter allowing a protrusion/indentation on the hub adapter to fully mate and seat. The angle of extender  90   a  can be set by the user using the features  63 ,  FIG. 7D  on adapter  60  which mate with corresponding features on the extender. In  FIG. 9G , a locking nut  91   a  is aligned and slipped over the threaded portion of the hub of the adapter. In  FIG. 9H , the locking nut  91   a  is tightened fully against the extender securing it in place. In  FIG. 9I , sprocket  70   a  is located and slid onto the front shaft again making sure the hex shaft is aligned and the sprocket is fully seated against the shaft revealing the shaft hole at the end of the shaft. Clip  72   a ,  FIG. 9J  is installed as shown in  FIG. 9K . In  FIG. 9L , track  30   a ′ is fully installed about sprockets  70   b ,  70   a , and idler  92   a  of extender  90   a . The same operation is performed on the other side of the robot resulting in the curb track configuration shown in  FIG. 3 . The track extenders can be angled upwardly or downwardly as desired. 
         [0032]    To configure the robot as shown in  FIG. 4  with both front and rear track extenders, rear extender  90   b ,  FIG. 10A  is located and slid over the rear hub aligning it at a flat angle as shown in  FIG. 10B . Front extender  90   a  is located and slid over the hub aligning it at the steep angle shown in  FIG. 10C . Stair climbing tread  30   a ″,  FIG. 10D  is positioned around the idler sprockets  92   a  and  92   b  of front extender  90   a  and rear extender  90   b , respectively. Front extender  90   a ,  FIG. 10E , is then rotated and aligned at an upward angle of 18° with respect to the horizontal as shown. Other angles for the front and rear track extenders are possible. 
         [0033]    As before, each extender is pushed flush onto its respective hub adapter allowing a protrusion/indentation feature on the hub adapter to fully mate and seat. The locking nut is then aligned and slipped over the threaded portion of the hub adapter and finger tightened locking it against the extender securing it in place,  FIG. 10F . In  FIG. 10G , sprocket  70   a  is installed on the front shaft using retainer clip  72   a ,  FIG. 10H . In  FIG. 10I , rear sprocket  70   b  is installed also using a retainer clip as discussed above resulting in track  30   a ″,  FIG. 10J  now installed about idler gears  92   a ,  92   b , and sprockets  70   a  and  70   b . The other track on the other side of the robot is installed in a similar fashion resulting in the configuration shown in  FIG. 4 . 
         [0034]    The result is a conversion system for easily converting a wheeled robot into a track driven robot in at least four possible configurations: the wheeled robot shown in  FIG. 1 , the track “off-road” configuration shown in  FIG. 2 , the track “curb-climb” configuration shown in  FIG. 3 , and the track “stair-climb” configuration shown in  FIG. 4 . A minimum number of parts are required, installation and removal of the wheels, the tracks, and track sprockets, and the track extenders is simple and can be accomplished, if necessary, in the field and with no tools. Reliability is enhanced, especially for the stair climbing configuration depicted in  FIG. 4 , via a preferred all wheel drive robot since de-treading on reduced wrap-angled tread drives is minimized. Thus, all the wheels and all the drive sprockets in the preferred embodiment are driven. 
         [0035]      FIGS. 11-12  depict a track extender  100  with tensioning mechanism  110 . Idler sprocket  112  is rotatably housed by slider  114  with opposing shoes (e.g., shoe  116 ) which slide in tracks  118   a  and  118   b  of paddle  120 . Screw  124  with jam nut  126  threaded thereon is threaded into the body of paddle  120  until the distal end of screw  124  abuts against plate  128  of slider  114 . By adjusting the screw  124 , slider  114  is thus extended and retracted relative to paddle  120  to tension or loosen the track. Jam nut  126  retains screw  124  in the desired position. Also featured is lock member  130  with pawl  132  biased over a rib  134  of lock nut  91  via spring plunger  136  to prevent lock nut  91  from turning once installed. Shoulder screw  138  retains lock member  130  to ear  140  extending from paddle  120 . For the rear track extenders, slider  114  is typically longer.  FIG. 12  also shows how features  63  on adapter  60  can interlock with corresponding features  65  on the inside of paddle  120  about orifice  67  to lock the angle of paddle  120  relative to the horizontal.  FIG. 12  also more clearly shows female threads of lock nut  91  which mate with male threads  61  of adapter  60 . 
         [0036]    Although specific features of the invention are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. The words “including”, “comprising”, “having”, and “with” as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed in the subject application are not to be taken as the only possible embodiments. 
         [0037]    In addition, any amendment presented during the prosecution of the patent application for this patent is not a disclaimer of any claim element presented in the application as filed: those skilled in the art cannot reasonably be expected to draft a claim that would literally encompass all possible equivalents, many equivalents will be unforeseeable at the time of the amendment and are beyond a fair interpretation of what is to be surrendered (if anything), the rationale underlying the amendment may bear no more than a tangential relation to many equivalents, and/or there are many other reasons the applicant can not be expected to describe certain insubstantial substitutes for any claim element amended. 
         [0038]    Other embodiments will occur to those skilled in the art and are within the following claims.