Abstract:
Postural stability platforms include at least one movement resistant element Fixed to a base and coupled to a plate. The plate is movable relative to the base but the movement resistant elements resist movement of the plate. Accordingly, subjects standing upon the plate are provided a degree of stability. The movement resistant elements may include springs, hydraulic cylinders, pneumatic cylinders, electromagnetic solenoids, and the like. Furthermore, in certain instances, the degree of resistance offered by a movement resistant element may be adjusted, such as by operation of a valve, so that the stability of the plate upon which the subject stands may vary depending upon the needs of the subject.

Description:
RELATED APPLICATIONS 
       [0001]    The present application claims priority to U.S. Provisional Application 60/670,084, filed on Apr. 11, 2005, and entitled BALANCE AND VESTIBULAR DISORDER DIAGNOSIS AND REHABILITATION, which is incorporated herein by reference. The present application also claims priority to U.S. Provisional Application 60/719,523, filed on Sep. 22, 2005, and entitled BALANCE AND VESTIBULAR DISORDER DIAGNOSIS AND REHABILITATION, which is also incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present application is related to postural stability. More particularly, the present application is related to platforms for assessing and/or rehabilitating postural stability. 
       BACKGROUND 
       [0003]    For various reasons, subjects may have the need to assess and/or rehabilitate their balance. For example, professional athletes may wish to improve their balance in order to improve their performance in their chosen sport. As another example, subjects suffering from medical conditions such as vestibular, orthopedic, neuromuscular, or neurological disorders may improve their medical condition through balance assessment and rehabilitation. 
         [0004]    Attempts have been made to manufacture postural stability platforms. However, these platforms may have drawbacks. For example, these platforms include a plate upon which the subject stands. This plate is suspended by an air bladder that is inflated and deflated by an air compressor. Among other problems that may arise, the air bladder and the air compressor are subject to malfunctions or failure. Furthermore, the support provided by the air bladder may be less than ideal. 
       SUMMARY 
       [0005]    Embodiments of the present invention address these issues and others by providing stability platforms that utilize one or more movement resistant elements such as hydraulic cylinders and/or springs to provide stability to the plate upon which the subject stands. Furthermore, in certain embodiments the degree of resistance to movement offered by the movement resistant elements is controllable, such as by a control knob that controls a position of a valve or other restrictive element that alters the resistance to movement. 
         [0006]    One embodiment is a postural stability platform that includes a base and a plurality of movement resistant elements fixed to the base. The postural stability platform further includes a rigid plate coupled to the movement resistant elements and pivotally coupled to the base such that the movement resistant elements resist movement of the plate relative to the base. 
         [0007]    Another embodiment is a stability platform that includes a base and at least one movement resistant element fixed to the base, the at least one movement resistant element containing a flowing substance. The postural stability platform further includes a rigid plate coupled to the at least one movement resistant element and movably coupled to the base such that the movement resistant elements resist movement of the plate relative to the base. The postural stability platform also includes a valve having adjustable positions and being in fluid communication with the at least one movement resistant element such that the position of the valve controls the degree of resistance created by the at least one movement resistant element. 
         [0008]    Another embodiment is a postural stability platform that includes a base and a rigid plate pivotally coupled to the base. The postural stability platform further includes at least one movement resistant element fixed to the base, the at least one movement resistant element having a shaft that is pivotally coupled to the rigid plate such that the movement resistant element resists movement of the plate relative to the base. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  shows a front perspective view of one embodiment of a stability platform. 
           [0010]      FIG. 2  shows a rear perspective view of one embodiment of a stability platform. 
           [0011]      FIG. 3  shows an exploded view of a center hub of one embodiment. 
           [0012]      FIG. 4  shows a partially exploded view of a base of one embodiment. 
           [0013]      FIG. 5  shows an exploded view of a cylinder head of the one embodiment. 
           [0014]      FIG. 6  shows a cross-sectional view of the cylinder head of one embodiment. 
           [0015]      FIG. 7  shows a cross-sectional view of a center post of one embodiment 
           [0016]      FIG. 8  shows an exploded view of a valve control system of one embodiment. 
           [0017]      FIG. 9  shows a schematic of a hydraulic system of one embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Embodiments of postural stability platforms provide one or more movement resistant elements to provide support for the subject standing on a balance plate of the platform. The one or more movement resistant elements may be cylinders that include shafts coupled to the balance plate. In certain embodiments, multiple movement resistant elements are present to provide stability in a number of directions of movement of the balance plate. In certain embodiments, one or more adjustable valves are present so that the adjustment to the valve alters the degree of resistance to movement. 
         [0019]      FIGS. 1 and 2  show one embodiment of a postural stability platform  100 . The platform  100  of this example includes many external features. The platform  100  includes a base assembly  102  that has a balance plate  104  coupled thereto. The balance plate  104  is movable relative to the base assembly  102  by the balance plate  104  having a pivot point at or near its center. The details of the pivot point of the balance plate  104  are discussed in more detail below. The balance plate  104  may include a non-skid sheet to prevent subjects from slipping. An example of such a non-skid sheet is the Safety-Walk® model 370 medium grade non-skid sheet by 3M Co. of St. Paul, Minn. The balance plate  104  of this example may be made of various rigid materials, such as metal, plastic such as acrylonitrile butadiene styrene (ABS), wood, and so forth. The size of the balance plate  104  is a matter of design choice but the diameter should exceed the largest expected foot size so that the foot of a subject can be entirely located atop the balance plate  104 . 
         [0020]    The base assembly  102  of this particular example includes various other features as well, such as individual sections  148 , top cover plates  149 , non-skid sheets  150  applied to the top cover plates  149 , and removable plugs  152 . The individual sections  148  allow for the base to be easily disassembled into pieces, transported, and reassembled. These individual sections  148  of this example may be made of similar rigid materials to the balance plate  104 . The top cover plates  149  of this example, which may of similar materials to the sections  148 , overlap between the individual sections to help hold the sections together. The non-skid sheet  150  may be included so that a subject does not slip when stepping onto and off of the base assembly  102 . The plugs  152  may be included to plug holes provided in the top cover plates  149 . The plugs  152  may be removed so that caster wheel assemblies can be accessed within the base assembly  102  in order to lower or raise the caster wheel assemblies and either mobilize or immobilize the stability platform  100 . 
         [0021]    To provide support, a member  106  is included that is mounted to the base assembly  102  and extends vertically. The member  106  of this example may be constructed of a rigid material, such as steel or wood, and is attached within the base assembly  102  to a rigid base discussed below. The member  106  provides a stable point upon which left and right support rails  112 ,  114  can attach. The support rails  112 ,  114  attach to the base assembly  102  and then extend vertically to attach to a hub  108  mounted atop the member  106 . The support rails  112 ,  114  may be made of various rigid materials such as metal or wood, and these support rails may include a soft covering such as foam rubber, neoprene, etc. to provide a comfortable hand-hold for a subject to use when stepping onto and off of the base assembly  102  and when steadying oneself while standing on the balance plate  104 . 
         [0022]    In this example, the hub  108  acts as a point of attachment for the support rails  112 ,  114  and also for a display mast  118 . The hub  108  may be constructed of a rigid material such as metal, wood and so forth and may have a shell made of ABS or other plastics or similar materials. A mounting bracket  116  is attached to the hub to allow the display mast  118  to be mounted in a movable relationship with the hub  108 . In this example, the mounting bracket  116  swivels within a hole  138  (shown in  FIG. 3 ) of the hub  108 . Furthermore, the bracket  116  has the ability to rotate forward and backward relative to the hub  106 . Thus, a video display device  120 , such as a liquid crystal display (LCD) screen, can be swiveled to be viewed from the front side or the rear side of the platform  100  and can be rotated forward or backward to improve the angle of viewing. The video display device  120  is attached to the mast  120  via a mounting bracket  136 , which also allows the vertical position of the video display device  120  to be altered to adapt to subjects of different heights. 
         [0023]    The video display device  120  of this example may be used for various purposes. For example, information about the subject may be displayed. A graphical user interface may be displayed to allow an operator and/or the subject to make selections regarding performing various balance assessment or rehabilitation routines and so forth. Graphical displays may then be provided for viewing by the subject while balancing on the balance plate  104  to produce a response by the subject to thereby assess and/or rehabilitate the balance of the subject. 
         [0024]    The stability platform  100  of this particular example is self-contained in that the display  136  as well as corresponding computer equipment is attached to the platform  100 . The computer equipment of this embodiment includes a central processing unit (CPU)  124  held in place by a bracket  122  that is attached to the member  106 . The CPU  124  is interconnected to the display device  120  to produce the visual displays for the operator and subject to view. The CPU  124  is also connected to a printer  128  resting on a shelf  126  that is attached to the member  106 . The printer  128  can be used to print information about the subject and the assessment and/or rehabilitation session. 
         [0025]    The CPU  124  is also connected to input devices such as a keyboard  132  and mouse  134  that both rest on a shelf  130  that is attached to the member  106 . The keyboard  132  and mouse  134  allows the operator and/or subject to interact with the graphical user interface. Other interface devices are applicable as well, such as remote controls that enables the operator to stand at a distance from the platform and also stand on the front side of the platform so that both the operator and the subject can simultaneously view the display device  120 . 
         [0026]    The CPU  124  may also be connected to a tilt sensor that is mounted to the balance plate  102 . The tilt sensor is discussed in more detail below. However, the CPU  124  may receive data from the tilt sensor that specifies the attitude of the balance plate  104  such that the CPU may monitor the movement of the balance plate  104 . Thus, the subject may be given visual feedback of the movement of the balance plate  104  via the display device  120  and this assessment and/or rehabilitation data may be stored for later review or comparison. 
         [0027]    In order to accommodate subjects of varying degrees of balance control, the platform  100  of this embodiment includes a mechanism for controlling how stable the balance plate  104  is. For a subject with very poor balance, it is likely necessary to assist the subject by providing a significant amount of stability to the balance plate  104  so that the balance plate  104  does not make large and sudden changes in position that could lead to ineffective assessment and/or rehabilitation sessions. 
         [0028]    The mechanism of this example includes a control know  110  mounted upon the hub  108 . As shown in  FIG. 3 , a center rod  140  passes up through the bottom of the hub  108 . This center rod  140  extends down the member  106  and into the base where it is then connected to a gear assembly as discussed below. At the hub  108 , the center rod  140  has a pin  141  running perpendicularly through it, and a metal insert  142  fits over the rod  140  and couples to the pin  141 . A spring  146  and ball  145  are positioned between the metal insert  142  and a plate  139  having holes  143 . The knob  110  fits over the metal insert  142  and thereby is coupled to the center rod  140  such that rotation of the knob  110  results in rotation of the center rod  140 . 
         [0029]    As discussed below, there may be various stability settings that can be selected by the knob  110 . To provide for these settings, the spring-biased ball  145  rests in one of the holes  143  of the plate  139 . Each hole  143  corresponds to a different stability setting as they center rod  140  must be rotated to move the ball  145  from one hole  143  to another. Markings may be provided on the plate  139  to illustrate the different settings, such as 0-11 plus a lock as the 12 th  position. Zero indicates a free balance plate  104  having the least stability. The lock at the 12 th  position indicates fixed balance plate  104  having complete stability for purposes of stepping onto and off of the balance plate  104 . 
         [0030]    As shown in  FIG. 4 , the base assembly  102  includes the individual sections  148 , each having an internal support structure  154  that includes holes for receiving the member  106  and for allowing the caster wheel assemblies  174  to be accessed. The torus-like shape of sections  148  rests upon and is fixed to a base plate  156 . 
         [0031]    The base plate  156  includes holes  182  that allow caster wheels  180  to be raised and lowered to immobilize or mobile that platform  100 . The caster wheels  180  are suspended by a bracket  176  mounted to the base plate  156  and having a bolt  178  threaded into it. The bolt  178  is coupled to the caster wheel  180  and extends up through the hole of section  148  to be exposed upon removal of the plug  152 . Turning the bolt  178  causes the caster wheel  180  to be raised or lowered. 
         [0032]    The stabilization mechanism of this example also includes a set of movement resistant elements that are coupled to the base plate  156  and to the balance plate  104 . The movement resistant elements may be of many forms. Some examples include springs, hydraulic cylinders, pneumatic cylinders, electromagnetic solenoids, and the like. As shown in this example, there are a set of cylinders  170 ,  196 ,  197 , and  198 . These cylinders may be hydraulic or pneumatic in nature. In this example, each of these cylinders includes a cylinder head  172  which pivotally coupled each cylinder to a support plate  158 . The balance plate  104  is then mounted to the support plate  158 . Examples of the cylinder head  172  and a hydraulic system are discussed in more detail below. 
         [0033]    The support plate is suspended over the base plate  156  by a center post  199  having a post head assembly  195  that also attached to the support plate  158 . The center post  199  provides a ball and socket type of joint with the post head assembly  195  as seen in  FIG. 7 . Thus, the support plate  158 , and hence the balance plate  104 , is free to pivot over a 360 degree range relative to the base plate  156 , and thus relative to the entire base assembly  102 . While this example provides for a pivotal connection of the support plate  158  that allows for a full 360 degrees of movement, the pivotal connection could be limited such as to a single axis in other embodiments. For example, the pivotal connection could restrict movement to an anterior-posterior axis of rotation of the balance plate  104 , or like wise, a left-right axis of rotation. 
         [0034]    In addition to the cylinders  170 ,  196 ,  197 , and  198 , this example provides a spring assembly  160  including springs  166 ,  168  spaced about a peripheral set of rings  162 ,  164 . The lower ring  164  is mounted via a bracket  165  to the base plate  156 . The balance plate  104  rests upon the upper ring  162 . The springs  166 ,  168  provide additional movement resistance but once compressed, assist the subject in returning the balance plate  104  to its neutral position. 
         [0035]    As shown, the springs alternate in length with one spring  168  having a greater length that extends from the upper ring  162  to the lower ring  164  while adjacent rings  166  have a shorter length such that compression of the longer spring  168  must take place prior to the shorter adjacent springs  166  becoming a factor in the movement of the subject. One example of springs are made of stainless steel of a gauge of 2.6 millimeters, a pitch of 10 degrees, and an inside diameter of 47 millimeters. In one embodiment, the longer spring  168  is 170 millimeters in uncompressed length while the shorter spring  166  is 100 millimeters in uncompressed length. 
         [0036]    Additional springs (not shown) may be included such as by placing them nearby the cylinders and coupling them to the base plate  158 . Furthermore, skirts (not shown) may be placed on the inside and/or outside of the rings  162 ,  164  to help support the springs hold them in place between the rings  162 ,  164 . 
         [0037]    In order to limit the amount of travel of the balance plate  104 , posts  171  may be included and spaced about the periphery. These posts  171  limit the amount of movement possible by the support plate  158 . A torus-like rubber bumper (not shown) may be positioned atop the posts  171  to provide 360 degrees of potential contact zones for the support plate  158 . 
         [0038]    A tilt sensor  105  is mounted to the support plate  158  so that data signals are produced that are indicative of the attitude of the balance plate  104  upon which the subject is standing. As discussed above, a computer system may receive these data signals and use them to provide immediate visual feedback to the subject, to compute characteristics of the balance capabilities of the subject, and to store for later review and analysis. The tilt sensor  105  may be of various types. One example is the SQ-SI-360DA Solid-State MEMS Inclinometer by Signal Quest of Lebanon, N.H. 
         [0039]    Returning to hydraulic system of this particular example,  FIGS. 5 and 6  show a cylinder head assembly  172 . The hydraulic cylinder  170  has a shaft  171  that extends vertically. Atop the shaft  171  sits a ball  186  and socket  184  joint that has external threads. A retaining member  188  has two concentric apertures of differing diameters. The smaller diameter aperture faces the cylinder  170  while the larger diameter aperture faces the support plate  158 . The smaller diameter aperture has a diameter larger than that of the connection of the socket join to the shaft  171 . 
         [0040]    A first ball bearing  190  that has a diameter smaller than the large diameter aperture but larger than the small diameter aperture sits within the large diameter aperture of the retaining member  188 . A ball bearing retaining disk  192  has a channel on each side and sits atop the first ball bearing  190  with the first ball bearing  190  being positioned within the bottom channel. A second ball bearing  194  sits atop the ball bearing retaining disk  192  and is positioned within the top channel. The retaining disk  192  has a threaded aperture that is tightened upon the threads of the socket  184 . The retaining disk  192  also sits within the large diameter aperture of the retaining member  188 . The retaining disk  192  has a smaller outside diameter than the diameter of the large aperture of the retaining member  188  which allows the retaining member  188  to have 360 degrees of movement relative to the shaft  171 . 
         [0041]    The retaining member  188  directly attaches to the support plate  158 . In doing so, the top ball bearings  194  contact the underside of the support plate  158  while the bottom ball bearings contact the retaining member  188  to thereby maintain a snug coupling of the shaft  171  to the support plate  158  while also allowing the support plate  158  to change its angle relative to the shaft  171  without binding. 
         [0042]    Returning to the mechanism for controlling the amount of stability provided to the balance plate  104 , the connection of the center rod  140  to adjustable valves  202 ,  204  is shown in  FIG. 8 . The center rod  140  extends down the member  106  until it reaches the interior of the particular base section  148  upon which the member  106  is mounted. Within that particular base section  148 , a gearbox assembly  201  is included to interconnect the center rod  140  to the adjustable valves  202 ,  204 . 
         [0043]    In this example, the gearbox includes a large drive gear  240  that is coupled to the center rod  140  via a ring  238 , a washer  242 , and a clamp  244 . Two smaller diameter spur gears  234 ,  236  are coupled to the shafts of the valves  204 ,  202  respectively to thereby provide a gear amplification from the center rod  140  to the valves  202 ,  204 . In one example, the large drive gear  240  has a diameter of 102 millimeters while the spur gears  234 ,  236  have a diameter of 18 millimeters. The center rod  140 , valves  202 ,  204 , gears  234 ,  236  are held in place by a support plate  232  and a mounting bracket  230  that is fixed to the base section  148 . 
         [0044]    Thus, rotation of the center rod  140  results in rotation of the control shafts of the valves  202 ,  204  to thereby change the degree to which the fluid channel of the valves  202 ,  204  is open. As the degree of opening increases, the resistance to the flow of fluid decreases. The resistance of the flow of the fluid provides the resistance to movement of the balance plate  104 . As discussed above, in one embodiment the control knob  110  has 12 positions, ranging from completely open valves and a free balance plate  104  to completely closed valves and a fixed balance plate  104 . 
         [0045]      FIG. 9  illustrates the hydraulic configuration of this example. It will be appreciated that there are other configurations possible, involving either fewer or more cylinders, fewer or more valves, and so forth. For example, there could be a single cylinder used for the anterior-posterior axis and a single cylinder used for the left-right axis. It will also be appreciated that the routing of the fluid lines may be changed. As shown, the top chamber of a cylinder of one axis is in fluid communication with the top chamber of an opposite cylinder of the same axis, and the likewise for the bottom chambers. It will be appreciated that the top chamber of a cylinder could instead be in fluid communication with a bottom chamber of the same cylinder, especially where a single cylinder is used for a given axis. 
         [0046]    In this particular example shown, the valve  202  is located in the fluid pathway between a bottom chamber  208  of cylinder  196  and bottom chamber  216  of cylinder  198 . This provides resistance in the anterior-posterior axis of movement. Likewise, the valve  204  is located in the fluid pathway between a bottom chamber  218  of cylinder  197  and a bottom chamber  212  of cylinder  170 . This provides resistance in the left-right axis of movement. The top chamber  206  of cylinder  196  is in fluid communication with the top chamber  214  of cylinder  198  while the top chamber  220  of cylinder  197  is in fluid communication with the top chamber  210  of cylinder  170 . The hydraulic hoses  229  that provide the fluid pathways are placed within the base assembly  102  and may be routed between the springs  166 ,  168 . 
         [0047]    This particular example also includes various three-way connectors  222 ,  224 ,  226 , and  228  that have valves as well. These three-way connectors with valves allows the hydraulic fluid to be injected into the fluid channels to fill the hoses  229  each of the chambers of the cylinders  170 ,  196 ,  197 , and  198 . One example of such hydraulic fluid is the Tellus® 37 weight oil by Shell Oil Co., of Houston, Tex. Pressure gauges may be connected to these three-way connectors  222 ,  224 ,  226 , and  228  with valves to pressurize the hydraulic system and to bleed away trapped air within the hydraulic system. For example, the hydraulic system may be pressurized to 150 pounds per square inch and then the balance plate  104  may be worked for about 30 minutes to bleed the air from the hydraulic system. 
         [0048]    Examples of the components of the hydraulic system of  FIG. 8  include model 160S-16SD25N50 hydraulic cylinders by TAIYO LTD of Osaka, Japan. Other examples include model FT1251 proportional valves and high pressure hoses by Kam Kee of Hong Kong. 
         [0049]    While the invention has been particularly shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various other changes in the form and details may be made therein without departing from the spirit and scope of the invention