Patent Publication Number: US-2013231217-A1

Title: Adaptive exercise device with variable components of motion

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of U.S. Provisional Patent Application 61/606,568 filed Mar. 5, 2012, and U.S. Provisional Patent Application 61/625,279 filed Apr. 17, 2012, the disclosures of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to exercise devices which simulate a running and stepping motion. In particular, the invention relates to an adaptive exercise device configured and operable to mechanically decouple the vertical and horizontal components of the foot and leg motion so as to allow a user to independently control the magnitude of both components of motion during the use of the device. 
     BACKGROUND OF THE INVENTION 
     There are a variety of exercise devices which attempt to simulate a running and stepping motion in which a user&#39;s feet and legs travel along a path having both vertical and horizontal components of motion. One group of such devices is termed “adaptive exercise devices” and such devices decouple the vertical and horizontal components of motion so that the horizontal component of foot and leg motion is independent of the vertical component of the motion of the foot and leg. In this manner, a user can implement a solely vertical foot and leg motion, a solely horizontal foot and leg motion, or a foot and leg motion which is a blended ratio of the two components. Systems of this type are known in the prior art, and one shortcoming of such prior art systems is that their mechanical construction mandates that the vertical component of the leg motion, even though decoupled from the horizontal component of foot motion, be of fixed magnitude. As such, these systems operate in an “all or nothing” mode with regard to vertical motion, and this limits the range through which a user&#39;s feet and legs may be exercised. Devices of this type are shown in U.S. Pat. No. 7,179,201. 
     As will be explained in detail hereinbelow, the present invention provides an improved adaptive exercise device which not only decouples vertical and horizontal components of foot and leg motion but also allows each of these components of motion to be independently varied in magnitude. As a result, the device of the present invention greatly expands the exercise options available to a user. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Disclosed is an adaptive exercise device which includes a frame which is configured to be supported on a floor. The device also includes a first and a second foot link each of which has a foot pad portion defined thereupon and configured to receive a user&#39;s foot. The device includes a primary guide assembly which engages the foot links and is configured and operable to direct the foot pad portions of the foot links along respective first paths of travel having equal and opposite, selectably variable, horizontal components of motion. The device includes a secondary guide assembly which includes a crankless reciprocating control system which is in mechanical communication with the foot links and is operable to reciprocate the foot links along respective paths of travel having equal and opposite, selectably variable, vertical components of motion. In the use of the device, the magnitude of the motion of the foot pads along the first paths of travel is mechanically independent of the magnitude of the motion of the foot pads along the second paths of travel. 
     In specific embodiments, the secondary guide assembly of the adaptive exercise device includes a first and a second secondary track pivotally supported at a pivot point defined upon the frame, and the reciprocating control system is operative to reciprocate the first and second secondary tracks about the pivot point along respective paths of travel having equal and opposite vertical components of motion; and in such embodiments, the foot links each engage a respective one of the first and second secondary tracks so as to be displaceable along the length thereof so that when the reciprocating control system reciprocates the secondary tracks along their respective paths of travel having the vertical component of motion, said vertical component of motion is communicated to a respective foot link so as to reciprocate the foot pad portion thereof along the second path of travel having the vertical component of motion. In some such embodiments, the secondary tracks may include an at least partially curved surface which engages a respective foot link. 
     In particular embodiments, the reciprocating control system may include one or more members selected from the group consisting of pulleys, springs, cables, rocker arms, and the like. In certain embodiments, the primary guide assembly may include a first and a second swing arm each of which is pivotally supported on the frame so that each swing arm is engaged in mechanical communication with a respective one of the foot links so as to at least partially support the foot links as they move along the first path of travel. In such embodiments, the swing arms may be mechanically coupled to their foot link either directly or via a connecting link. In other embodiments, the primary guide assembly may also include at least one primary track which is configured and operative to engage and direct the first and second foot links along the first path of travel. 
     In specific embodiments, the device may include one or more resistance devices in mechanical communication with the primary guide assembly and/or the secondary guide assembly. Such resistance devices may comprise one or more of a fan device, a frictional brake device, a fluidic device, a magnetic device, a pendulum, a flywheel, and a resilient member. 
     In another group of embodiments, the reciprocating control system may include an oscillating arm device which includes a first and a second arm coupled thereto so that said arms are pivotally supported so as to be movable in equal and opposite directions relative to the frame of the device. In these embodiments, each arm of the oscillating arm device is coupled to a respective one of the foot links so as to reciprocate that foot link and its associated foot pad portion along the second path of travel having the vertical component of motion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic depiction of one embodiment of adaptive exercise device in accord with the present invention; 
         FIGS. 2A-4B  illustrate some specific crankless, reciprocating control systems which may be utilized in the practice of the present invention; 
         FIG. 5  shows an alternative foot link arrangement utilized in connection with another embodiment of exercise device in accord with the present invention; 
         FIG. 6  shows another embodiment of adaptive exercise device in accord with the present invention; 
         FIG. 7  shows yet another embodiment of adaptive exercise device in accord with the present invention; 
         FIGS. 8A and 8B  show alternative variations of primary guide assemblies which may be utilized in the practice of the present invention; 
         FIG. 9  shows another embodiment of adaptive exercise device of the present invention in which the foot links thereof are directly reciprocated by a reciprocal controller of the secondary guide assembly; 
         FIG. 10  is a schematic depiction of another adaptive exercise device of the present invention; 
         FIG. 11  shows some various paths of motion which may be achieved through the use of an adaptive exercise device of the present invention; 
         FIG. 12  shows yet another embodiment of an adaptive exercise device in accord with the present invention including an oscillating arm assembly; 
         FIG. 13  is an end view of the oscillating arm assembly of  FIG. 12 ; 
         FIG. 14  shows the exercise device of  FIG. 12  in a first position in which foot motion is essentially along a path having a primarily horizontal component of motion; 
         FIG. 15  is an end view of the oscillating arm assembly as positioned with regard to  FIG. 14 ; 
         FIG. 16  shows the adaptive exercise device of  FIG. 12  in a second position in which foot motion is essentially along a path of travel having a primarily vertical component of motion; 
         FIG. 17  is an end view of the oscillating arm assembly as positioned with regard to  FIG. 16 ; 
         FIGS. 18A-18C  show some particular resistance devices as incorporated into the oscillating arm assembly of the  FIG. 12  device; and 
         FIG. 19  shows another embodiment of an adaptive exercise device of the present invention having a reciprocal controller which includes an oscillating arm assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention may be implemented in a number of different configurations and will be explained with regard to some specific embodiments. It is to be understood that other modifications and variations are within the scope of this invention and will be readily apparent to those of skill in the art in view of the teaching of this disclosure. 
     The device of the present invention operates to simulate a running and stepping motion and includes a frame which is configured to be supported on a floor or other such support surface. The device further includes a first and a second foot link, each having a foot pad portion which receives and supports a user&#39;s foot. A primary guide assembly engages the foot links and directs the foot pad portions along a first path of travel having a horizontal component of motion and a secondary guide assembly is in mechanical communication with the foot links and reciprocates them along respective paths of travel having equal and opposite vertical components of motion. The device is configured so that the magnitude of both the horizontal and the vertical component of motion communicated to the foot links may be readily and independently varied by a user in the course of employing the apparatus. 
     Prior art adaptive exercise devices utilize a crank-based mechanism for controlling the vertical and/or horizontal components of foot motion; and in accord with the present invention, it has been found that the circular component of the crank motion mandates that any reciprocating motion of the user&#39;s foot which is dependent on the crank-based mechanism be of a fixed and predetermined value. Hence, prior art adaptive exercise devices, while allowing a user to control the horizontal component of foot motion, restrict a user&#39;s foot to a vertical path of travel which is either zero or of a fixed length. 
     A further shortcoming of crank-based control systems is that crank linkages inherently produce a “dead spot” from which it is difficult to initiate motion, thereby interfering with the smoothness of the foot motion which they provide. As will be explained hereinbelow, the present invention utilizes a crankless linkage to reciprocate a user&#39;s foot in the vertical and/or horizontal direction. While devices of the present invention are crankless with regard to the guide elements which reciprocate a user&#39;s foot in a vertical and/or horizontal direction, it is possible the adaptive exercise devices of the present invention may include crank elements in conjunction with portions of the device not directly operative to provide a variable, reciprocal foot motion. 
     Referring now to  FIG. 1 , there is shown one embodiment of adaptive exercise device in accord with the present invention. The device includes a frame  12  which supports the remainder of the apparatus on a floor or other such support surface. The device further includes a first  14   a  and a second  14   b  foot link each of which is configured to support a user&#39;s foot on a foot pad portion thereof. The foot links  14   a ,  14   b  are in communication with a primary guide assembly which directs the foot links along a first path of travel having a horizontal component of motion. In this instance, the primary guide assembly comprises a first swing arm  16   a  and a second swing arm  16   b  which are pivotally supported on the frame  12  and connected to their respective foot links. As will be understood in the art, the swing arms  16   a ,  16   b  will typically be mechanically coupled together so as to move in equal and opposite paths of travel. Such coupling mechanisms may include gearing arrangements. 
     The device of  FIG. 1  further includes a secondary guide assembly which is in mechanical communication with the foot links  14   a ,  14   b  and which operates to reciprocate them along respective paths of travel having equal and opposite vertical components of motion. In the  FIG. 1  embodiment, the secondary guide assembly includes a first and a second secondary track  18   a ,  18   b  which are pivotally supported on the frame  12  at a pivot axis  20  defined thereupon. The secondary guide assembly further includes a reciprocating control system (not shown in  FIG. 1 ) which reciprocates the first and second tracks  18   a ,  18   b  about the pivot axis  20  in the direction generally shown by arrow A. This reciprocal, pivotal motion of the tracks  18   a ,  18   b  has a substantially vertical component of motion which in turn is communicated to the foot links  14   a ,  14   b . Furthermore, the foot links  14   a ,  14   b  engage their respective secondary tracks  18   a ,  18   b  by rollers  22   a ,  22   b  which, in addition to supporting the foot links on the secondary tracks, allow the foot links to move there along in a path of travel having a substantially horizontal component as shown by arrow B. In this manner, the vertical and horizontal components of motion are decoupled. Furthermore, the magnitude of the vertical component of motion of the secondary control system and associated track is not fixed, as is the case with prior art crank wheel based control systems. The crankless control system of the present invention allows for a user to choose an appropriate degree of vertical motion while the device is in use. As will be explained in detail hereinbelow, the reciprocating control system of the secondary guide assembly is configured so that the vertical motion selected by the user is imparted equally and oppositely to each of the foot links. 
     There are a variety of configurations in which the reciprocating control system of the present invention may be implemented, with the primary requirement being that the system provides equal and opposite vertical motion over a user-selected range of values. Such control systems may be implemented utilizing mechanical components such as pulleys, springs, elastic bodies, cables, rollers, rocker arms, and the like as well as through the use of fluidic devices such as hydraulic or pneumatic cylinders, dampers, pistons, and the like. Referring now to  FIG. 2A , there is shown a portion of an exercise device in which a crankless, reciprocating control system comprises a pulley  24  operating in conjunction with a cable  26  so as to raise and lower components of the device which may comprise secondary tracks  18   a ,  18   b  or foot links, depending on device configuration.  FIG. 2B  shows an end view of this embodiment of reciprocating control system. 
       FIGS. 3A and 3B  show side and end views respectively of another reciprocating control system in accord with the present invention. This system is based upon the use of two fluidic devices such as hydraulic or pneumatic cylinder/piston arrangements. As will best be seen from  FIG. 3B , two cylinders  28   a  and  28   b  are coupled together so that compression of a liquid or gaseous fluid in one cylinder will be communicated to the other cylinder driving it in an equal and opposite direction, and this motion is again conveyed to further elements of the apparatus such as foot links or secondary tracks  18   a ,  18   b . As further seen in  FIG. 3A , a pair of springs  30   a ,  30   b  or other such resilient elements optionally may be incorporated into the apparatus so as to better coordinate the motion of the two elements. 
     Yet other configurations of reciprocating control systems may be implemented, and one such embodiment is shown in  FIGS. 4A and 4B . As shown in  FIG. 4A , a pair of cables  32   a ,  32   b  joins foot links or secondary tracks  18   a ,  18   b  to corresponding rocker arms  34   a ,  34   b  which are supported on the frame  12  of the device. The cables  32   a  and  32   b  are also coupled to a reciprocating arm  35 , which is shown in an end view in  FIG. 4B . The motion of the reciprocating arm  35  raises and lowers the cables  32   a  and  32   b , causing them to raise and lower their respective rocker arms  34   a  and  34   b , thereby reciprocating the secondary tracks  18   a  and  18   b . As will be understood, yet other embodiments of reciprocating control systems may be implemented utilizing equivalent components, and such will be apparent to those of skill in the art in view of the teaching presented herein. 
     In the context of this disclosure, the primary guide assembly is described as functioning to direct the foot links along respective first paths of travel having equal and opposite, selectably variable, horizontal components of motion, and the secondary guide assembly is described as functioning to direct the foot links along respective first paths of travel having equal and opposite, selectably variable, vertical components of motion. It is to be understood that these paths of travel may not be precisely equal, owing to play in the mechanical components of the control systems, geometric factors, such as the inclination of the foot links in the use of the device, kinematic factors of the user&#39;s motion, and the like. Hence, the term “equal” is understood to allow for some minor variation in respective lengths, provided that the opposite paths are substantially similar. 
     Referring now to  FIG. 5 , there is shown yet another embodiment of exercise device in accord with the present invention. Specifically shown is an alternative foot link arrangement in which foot links are joined to their respective swing arms  16   a ,  16   b  by links  38   a ,  38   b . As in the previous embodiment, the secondary guide assembly includes secondary tracks  18   a ,  18   b  which are pivotally supported upon the frame  12 . As discussed, a crankless, reciprocating control system operates to move the secondary tracks in a vertical path of travel. 
     Referring now to  FIG. 6 , there is shown another embodiment of the present invention in which the primary guide assembly incorporates a primary track  40  which engages the foot links  14   a ,  14   b  by rollers  42   a ,  42   b . As in the previous embodiment, the secondary guide assembly includes secondary tracks  18   a ,  18   b  which are pivotally supported on the frame. A reciprocating control system  50 , which may be in accord with the description herein, serves to reciprocate the secondary tracks  18   a ,  18   b . As will be seen, the foot links  14   a ,  14   b  engage the secondary tracks  18   a ,  18   b  by rollers  52   a ,  52   b.    
     Referring now to  FIG. 7 , there is shown another embodiment of device generally similar to that of  FIG. 1 , except that the secondary guide assembly includes a pair of curved tracks  54   a ,  54   b  which are joined together in a parallel relationship by tie rods  56   a ,  56   b . These tie rods are in turn pivotally supported so as to be free to rock in a back-and-forth motion such that tracks  54   a ,  54   b  are reciprocated in complementary up-and-down motions. This reciprocation is implemented utilizing a reciprocating control system shown generally at reference numeral  50 . As in the previous embodiment, the primary control system is implemented utilizing swing arms. As further will be seen from  FIG. 7 , a spring, elastic member, flexible rod, or other such resilient body may be incorporated into the device so as to provide resistance with regard to the primary control system, and hence the horizontal component of motion of the foot links. As specifically shown, a spring  58  is disposed to anchor the swing arm  16  to the frame  12 . As will be understood, this element could be otherwise configured and/or placed. 
     While  FIG. 7  shows a first resistance device  58 , in mechanical communication with the primary guide assembly, for providing resistance in connection with the horizontal component of motion of the foot links, it is to be understood that a second resistance device may also be included in mechanical communication with the secondary guide assembly. This second resistance device will function to provide resistance with regard to the vertical component of motion of the foot links. Resistance devices may be utilized with any and all embodiments of this invention. The first and second resistance devices may be identical or they may differ, and they may, by way of example and not limitation, comprise flywheel assemblies, fan devices, frictional brake devices, fluidic devices, and magnetic devices, as well as resilient members as noted above. The resistance devices may be operable to provide a fixed degree of resistance, or they may be adjustable to provide a variable degree of resistance. Inclusion of any resistance device is optional in the practice of the present invention, and it should be noted that in some particular instances, variable resistance devices may be associated with only one of the guide assemblies. 
       FIGS. 8A and 8B  show other variations of the primary guide assembly. In  FIG. 8A , foot pads are disposed directly upon tracks  18   a ,  18   b  which reciprocate about a pivot axis defined by a roller  54  which also permits horizontal motion of the tracks. As in the previous embodiments, vertical motion is imparted to the tracks  18   a ,  18   b  by a reciprocating control system of the type described herein. The embodiment of  FIG. 8B  incorporates a primary track  40  as part of the primary guide assembly and allows for horizontal motion of the foot links. As in the previous embodiments, a reciprocating control system, not shown, moves the secondary tracks in the vertical direction. 
     Referring now to  FIG. 9 , there is shown another embodiment of the present invention in which the foot links  14   a ,  14   b  are directly reciprocated by a reciprocal controller  50  of the secondary guide assembly without the use of any secondary tracks. As in the  FIG. 1  embodiment, the foot links  14   a ,  14   b  are moved in a horizontal direction by the swing arms  16   a ,  16   b  which constitute the primary control system. As noted previously, the reciprocal controller  50  may be variously configured in accord with the teaching presented herein. 
     Referring now to  FIG. 10 , there is a schematic drawing of an exercise device of the present invention including a particularly configured reciprocal controller  50 . In this embodiment, the controller  50  includes a first rocker arm  60   a  and a second rocker arm  60   b  which are supported by the frame  12 . Each rocker arm  60   a ,  60   b  contacts a respective secondary track  18   a ,  18   b  via a roller  62   a  and  62   b . As in previous embodiments, the secondary tracks  18   a ,  18   b  are pivotally supported by the frame. The rocker arms  60   a ,  60   b  are interconnected via a cable  26  supported by an associated pulley  24 . The inclusion of the cable synchronizes the motion of the two secondary tracks  18   a ,  18   b  so that their motion will be equal and reciprocal. 
     The  FIG. 10  embodiment includes a pair of foot links  14   a ,  14   b  which, as in the  FIG. 1  embodiment, are coupled to respective swing arms  16   a ,  16   b  which in turn are pivotally supported by the frame  12 . The foot links  14   a ,  14   b  are supported upon respective secondary tracks  18   a ,  18   b  by associated rollers  22   a ,  22   b , as in the  FIG. 1  embodiment. However, in the  FIG. 10  embodiment, the secondary tracks  18   a ,  18   b  include curved faces which engage the rollers  22 . This curvature operates to provide a camming action which modifies the horizontal motion of the foot links  14   a ,  14   b , and by choosing a specific camming surface, a desired profile of foot motion may be selected. 
     Referring now to  FIG. 12 , there is shown yet another embodiment of an adaptive exercise device in accord with the present invention. As in the prior embodiments, the device includes a frame  12  which supports at least a portion of the remainder of the apparatus on a floor or other such surface. The  FIG. 12  embodiment includes a first and a second foot link which are each configured to support a user&#39;s foot typically on a foot pad portion thereof. In the  FIG. 12  embodiment, only a single foot link  14   a  is shown and it is to be understood that a second foot link  14   b  is disposed directly there behind and not visible. The device of  FIG. 12  includes a primary guide which is constituted by a pair of swing arms, and in this figure only a single swing arm  16   a  is visible and a second swing arm is disposed there behind. As in the previous embodiments, the swing arms  16  are pivotally supported upon the frame  12  and mechanically coupled so as to move in equal and opposite paths of travel. The swing arms  16  are likewise coupled to their respective foot links  14  and operate to direct the foot links along a path of travel having a substantially horizontal component of motion. 
     The embodiment of  FIG. 12  includes a secondary guide assembly which incorporates a crankless reciprocating control system in mechanical communication with the foot links. The reciprocating control system is operative to reciprocate the foot links along respective paths of travel having equal and opposite vertical components of motion which are mechanically independent of the motion of the foot links along the first, horizontal path of travel. In this embodiment, the reciprocating control system includes a pair of cables  26   a ,  26   b  which are connected to their respective foot links  14 . The cables are also connected to an oscillating arm assembly  80  which includes a first arm  82   a  and a second arm  82   b  which are mechanically coupled together and supported by a journal bearing  84 , which in turn is supported upon the frame  12 .  FIG. 13  is an end view of the oscillating arm assembly  80 . As will be seen, the oscillating arm assembly  80  and associated cables  26   a ,  26   b  cooperate to allow the foot links  14  to pivot at their connection points to their respective swing arms  16  so as to move the foot pad portion of the foot link along a path of travel having a substantially vertical component. It will be further appreciated that the nature and construction of the reciprocal control system provides for motion which is independent of the fore and aft motion provided by the primary control system and is also variable in terms of magnitude, while being equal and opposite with regard to each of the foot links. In this manner, vertical and horizontal components of foot motion are independently variable over a user-selected range of motion. 
       FIG. 14  shows the device of  FIG. 12  in a first position in which foot motion is essentially along a path having a primarily horizontal component of motion. In this regard, the primary control system constituted by the arm links  16   a  and  16   b  is operative to move the respective foot links  14   a ,  14   b  along a fore-aft path. In the  FIG. 14  configuration, the reciprocal control system is not operating to provide any vertical motion to the foot links; however, it will be noted that the cables  26   a ,  26   b  assist in supporting the foot links while allowing fore-aft motion.  FIG. 15  is an end view of the device better illustrating the position of the oscillating arm assembly  80 . 
       FIG. 16  shows the device of  FIG. 12  in a mode of operation in which the reciprocal controller of the secondary control system is operative to provide for motion of the foot links  14   a ,  14   b  along a path of travel having a primarily vertical component of motion. In this regard, the oscillating arm assembly  80  has pivoted about its support point in the journal bearing  84  so that the first arm  82   a  thereof is in a substantially vertical orientation and has correspondingly raised the first foot link  14   a . Likewise, the second arm  82   b  is in a substantially horizontal orientation and has lowered the second foot link  14   b . Given the coupling of the foot links via the oscillating arm assembly, it will be appreciated that the motion of the foot links along a vertical path will be equal and opposite, and the magnitude of this motion may be selectably controlled by the user. It will thus be appreciated from a review of  FIGS. 14-17  that a combination of vertical and horizontal foot motion may be selectably controlled by the user so as to provide various combinations of foot travel. 
     The device of  FIGS. 12-17  may also be configured to incorporate one or more resistance devices in combination with the reciprocating control system. For example, as shown in  FIG. 18A , the device may include fluidic cylinders  28   a ,  28   b  such as hydraulic cylinders or pneumatic cylinders; and as is known in the art, these cylinders may be made adjustable so that the degree of resistance can be varied. As shown in  FIG. 18B , the device may similarly include resilient bodies such as springs  30   a ,  30   b , as well as elastic bands, flexible members, and the like. As shown in  FIG. 18C , the device may also incorporate a pendulum  88  which will provide for kinetic resistance. As shown, the pendulum may be configured so that its weight is adjustable. Other variable resistance devices such as flywheels, frictional devices, magnetic devices, fans, and the like may likewise be incorporated. While the resistance devices of FIGS.  18 A- 18 C are shown as being in direct mechanical engagement with the oscillating arm assembly  80 , it is to be understood that they may be otherwise disposed. 
     Referring now to  FIG. 19 , there is shown yet another embodiment of an adaptive exercise device in accord with the present invention. The embodiment of  FIG. 19  is generally similar to the embodiment of  FIGS. 12-17  previously discussed; however, in this embodiment the oscillating arm assembly  80  has been moved to the front portion of the apparatus, and the cables thereof  26   a ,  26   b  are directed to the rear of the device by means of pulleys  90   a ,  90   b  so as to engage the rear portion of the foot links  14  as in the prior embodiment. In view of this teaching, it will be further appreciated that the reciprocating control system may be otherwise disposed. 
     The present invention may be implemented in yet other embodiments utilizing other configurations of primary and secondary control systems. For example, the various track members used in the primary and/or secondary control systems may be curved or of some other non-linear configuration. Also, as noted above, other configurations of reciprocal control systems may be utilized in the present invention. 
     It is to be understood that through the use of the present invention the vertical and horizontal components of foot motion are under completely independent control. In this manner, both vertical and horizontal motion may be varied from zero to full mechanical range of the device. This will allow for foot motion to be varied over a number of different patterns, and some such patterns are shown schematically in  FIG. 11 . 
     In view of the teaching presented herein, yet other modifications and variations of this invention will be readily apparent to those of skill in the art. The foregoing drawings, discussion, and description are illustrative of some specific embodiments of the invention but are not meant to be limitations upon the practice thereof. It is the following claims, including all equivalents, which define the scope of the invention.