Abstract:
A walking training device provides substantial fixation of the user&#39;s feet against a movable footplate in the direction of the user&#39;s stride while allowing toe lift and heel lift necessary for natural walking. The harness system provides an approximation of a shallow crossed four-bar linkage to provide angulation without substantial translation.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     CROSS REFERENCE TO RELATED APPLICATION 
     BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a device for training human limb motion and in particular to a device that trains a walking user. 
         [0002]    Walking impairment can be caused by disorders of the central nervous system, peripheral nervous system, and musculoskeletal system. Strokes, for example, which occur when blood flow to a region of the brain is obstructed, are a leading cause of severe long-term disability. Studies have shown that while many stroke sufferers have adequate strength at each joint, for example, for walking, the stroke may make it difficult for the sufferer to coordinate this strength for walking. 
         [0003]    Rehabilitation efforts for stroke victims often use conventional exercise equipment to retrain correct limb motion. Such exercise equipment, for example, a stationary bicycle, provides resistance along a constrained path of movement that is intended to approximate a desired path of movement that the patient is trying to learn. This constraint may hide basic errors in muscle activation patterns and/or promote compensating behaviors by the patient without addressing the underlying muscle activation errors. 
         [0004]    Effective training of walking can be difficult because some constraint on the motion of the patient is required to keep the patient safe, to couple the patient to the training device for measurement, and to apply training motion and forces. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention provides a harness that may be used to provide mechanical coupling between a patient&#39;s feet and footplates on a training apparatus, where the footplates are supported for forward and backward motion and/or force measurement. The harness accommodates the heel lift and toe lift needed for natural walking while still closely coupling the patient&#39;s foot to the footplate with respect to motion along the stride axis. In this respect, the invention provides a balancing between foot motion guidance and foot motion freedom to permit effective training of disordered walking. 
         [0006]    Specifically, in one embodiment, the invention provides a walking training apparatus having left and right footplates for support of a standing patient having one foot on the left footplate and one foot on the right footplate so that a front portion of each footplate is proximate to the patient&#39;s toes and a rear portion of each footplate proximate to the patient&#39;s heel. Left and right footplate support assemblies provide at least one of forward and backward motion of the left and right footplate along a stride axis of the patient and measurement of forces by the patient against the left and right footplate. A left and right harness releasably attach the patient&#39;s feet to the left and right footplates, each harness providing: (a) a first flexible tension element flexibly extending between a front of the patient&#39;s foot and an attachment point at a rear of each footplate and (b) a second flexible tension element flexibly extending between a rear of the patient&#39;s foot and an attachment point at a front of each footplate. 
         [0007]    It is thus a feature of at least one embodiment of the invention to provide a harness attachment that substantially prevents slippage between the foot and footplate while allowing heel lift, toe lift, and minor eversion, inversion, and axial rotation necessary for a normal stride. 
         [0008]    The first flexible tension element may provide a toe pocket receiving a toe of a shoe worn by the patient, and the second flexible tension element provides a heel pocket receiving a heel of a shoe worn by the patient. 
         [0009]    It is thus a feature of at least one embodiment of the invention to provide a harness that works with a shoe (including the patient&#39;s own shoes) to provide a simple robust attachment to the patient&#39;s feet. 
         [0010]    The harness may further include length-adjustable connections between the first flexible tension element and second flexible tension element allowing respective pockets of the first flexible tension element and second flexible tension element to be drawn together about a patient&#39;s shoe. 
         [0011]    It is thus a feature of at least one embodiment of the invention to provide a harness that may accommodate a variety of different patient and shoe sizes. 
         [0012]    The length-adjustable connections may include buckles permitting separation of the first flexible tension element and second flexible tension element. 
         [0013]    It is thus a feature of at least one embodiment of the invention to simplify attachment and detachment of the harness by allowing separation of the harness into two elements. 
         [0014]    The first flexible tension element and second flexible tension element may be woven straps sewn to form open pouches providing the toe pocket and heel pocket 
         [0015]    It is thus a feature of at least one embodiment of the invention to provide a flexible harness constructed of woven straps having high tensile strength that may be securely attached to the shoe. 
         [0016]    The first flexible tension element may provide two flexible bands extending from left and right sides of the toe pocket to a pair of attachment points at the rear of each footplate flanking at least one flexible band extending from the heel pocket to at least one attachment point at the front of each footplate. 
         [0017]    It is thus a feature of at least one embodiment of the invention to provide additional stability to the toe of the patient&#39;s feet as they advance in the normal stride. The flanking arrangement prevents interference between the tensile elements. 
         [0018]    The attachment point of the first flexible tension element and the second flexible tension element to the footplate may provide a releasable connection releasing under a predetermined force achievable by leg strength alone. 
         [0019]    It is thus a feature of at least one embodiment of the invention to provide a harness that may be rapidly released from the footplate by the patient if necessary, for example, to regain balance. 
         [0020]    The attachment points may be provided by inter-engaging hook and loop fastener material. 
         [0021]    It is thus a feature of at least one embodiment of the invention to provide a releasable attachment mechanism that is relatively resistant to shear forces generated during a normal stride but easily separated, for example, by upward lifting of the foot. 
         [0022]    The harness may further include an electrical sensor attached to at least one of the first flexible tension element and second flexible tension element to provide an indication of a predetermined separation of at least one first flexible tension element and, second flexible tension element from its respective left or right footplate. 
         [0023]    It is thus a feature of at least one embodiment of the invention to allow the harness to signal a stepping off of the footplate, for example, to provide an indication to a healthcare professional or to affect operation of the walking apparatus. 
         [0024]    The electrical sensor may be an electrical conductor attached to at least one of the first flexible tension element and second flexible tension element communicating with at least one releasable electrical connector to break a circuit at the predetermined separation of at least one first flexible tension element and second flexible tension element from its respective left or right footplate. 
         [0025]    It is thus a feature of at least one embodiment of the invention to provide an electrical sensor that naturally fails in a safe mode by signaling not only when the patient&#39;s foot is removed from the footplate but also if the sensor wire or connectors are broken. 
         [0026]    The walking training apparatus may include motors for providing forward and backward motion of the left and right footplate along the stride axis and a controller communicating with the electrical sensor and the motors to respond to the indication for stopping motion of the footplates. 
         [0027]    It is thus a feature of at least one embodiment of the invention to allow any motorized motion of the footplates to be immediately stopped if the patient loses contact with the footplates. 
         [0028]    The controller and the motors may provide for a periodic forward and reverse motion of the left and right footplates to mimic a natural stride in which the footplates move out of phase with respect to each other. 
         [0029]    It is thus a feature of at least one embodiment of the invention to provide a harness particularly suitable for motor-actuated footplates that permits natural stride under such circumstances. 
         [0030]    The footplate support assemblies may provide measurements of force applied by the footplate to the footplate support and may include an output display for displaying the measurements of force. 
         [0031]    It is thus a feature of at least one embodiment of the invention, to provide a harness that accommodates instrumentation of leg and foot forces during contact with the footplates. This force measurement may be used to control the footplate motor actuation. 
         [0032]    The walking training apparatus may include a framework holding the footplates and footplate supporting assemblies, the framework providing upwardly extending support structures attached to restrain lines communicating with a shoulder and hip harness receivable by the patient&#39;s shoulders and hip to provide motion restraint on a patient supported on the footplates during walking. 
         [0033]    It is thus a feature of at least one embodiment of the invention to provide for angular stabilization for patients attempting to relearn balance during walking. 
         [0034]    The restraints may provide a nonlinear spring-biasing force to the shoulder and hip harness. 
         [0035]    It is thus a feature of at least one embodiment of the invention to allow the patient to explore the boundaries of their balance capabilities without risk of falling by providing relatively low restoring force for low angular displacements rising quickly to a stiff restraining force for high angular displacements. 
         [0036]    The restraints may communicate with force and angle sensors mounted to the framework to indicate forces and angles of forces applied to the harnesses by the patient during walking. 
         [0037]    It is thus a feature of at least one embodiment of the invention to provide measurements of walking ability to provide positive feedback to the patient or analysis of the patient&#39;s walking problems for better training. 
         [0038]    These particular objects and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0039]      FIG. 1  is a left-side, elevational view of a walking training apparatus of the present invention showing a patient standing on left and right footplates while walking and supported by stabilizing restraints communicating with the patient&#39;s hip and shoulder harness; 
           [0040]      FIG. 2  is a top plan view of the walking training apparatus of  FIG. 1 ; 
           [0041]      FIG. 3  is a phantom view of a force-sensitive actuator to which the stabilizing restraints are attached and which may measure force magnitude and force angle on the restraints; 
           [0042]      FIGS. 4 a  and 4 b    are fragmentary perspective views of a section of the stabilizing restraints in differing extensions demonstrating the non-linear elastic properties of the restraints; 
           [0043]      FIG. 5  is a top plan view of one footplate of  FIG. 1  showing a shoe attached by a shoe harness and safety wire to the footplate; 
           [0044]      FIG. 6  is a perspective view of a toe portion of the harness of  FIG. 5 ; 
           [0045]      FIG. 7  is a perspective view of the heel portion of the harness of  FIG. 5 ; 
           [0046]      FIG. 8  is a simplified side view of the patient&#39;s foot during a forward leg extension of a normal stride showing a toe lift accommodated by the harness; 
           [0047]      FIG. 9  is a figure similar to that of  FIG. 8  showing a centerpoint of a nasal stride showing the foot without toe lift or heel lift; and 
           [0048]      FIG. 10  is a figure similar to  FIGS. 8 and 9  showing a rear leg extension of the normal stride and resulting heel lift accommodated by the harness. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0049]    Referring now to  FIGS. 1 and 2 , a walking training apparatus  10  may provide for a framework  12  providing generally a horizontal rectangular platform  14  supported against the floor. The framework  12  may provide columns  16  extending upward from the corners of the platform  14  to a point above the shoulder height of an average patient  15  standing on the platform  14 . 
         [0050]    Beneath an upper surface of the platform  14 , a bearing track  18  extends generally along a stride axis  20  aligned with a stride direction of the patient  15 . The stride axis  20  is generally the direction of motion of the patient&#39;s feet during walking. The bearing track  18  supports left and right carriages  22  for sliding along the bearing track  18 . Each of the left and right carriages  22  provides a portion which extends upward through the upper surface of the platform  14  to attach to corresponding left and right footplates  24   a  and  24   b.  The footplates  24  are generally coplanar and horizontal and may receive and support the patient&#39;s 15 feet during walking motion. 
         [0051]    Servomotors  25  connect via belts to the carriages  22  to provide controlled motion of the footplates  24  in the direction of the stride axis  20  under the control of a computer/controller  26 . As is understood in the art, the computer/controller  26  may include a processor and computer memory, the latter of which may hold programs stored in non-transient media for implementing various operations to be described below. The computer/controller  26  may be positioned adjacent to the framework  12  and may communicate with a display  27  visible by the patient  15  walking in the walking training apparatus  10  for receiving visual guidance during walking training. 
         [0052]    The carriages  22  will preferably include instrumentation (for example, load cells) measuring forces along each of three Cartesian axes (positive and negative forces along each axis) and torques about each of the Cartesian axes (positive and negative torques along each axis). These measurements will be communicated to the computer/controller  26  and may provide for the display of information derived from these measurements on the display  27 . 
         [0053]    A shoulder harness  28  and hip harness  30  fit about the shoulders and hips of the patient  15 , respectively, and communicate by means of flexible restraint straps  32  with force sensitive actuators  34  attached to the columns  16  at shoulder and hip height, respectively. Thus, four restraint straps  32  separated in a horizontal plane by approximately 90 degrees communicate between the shoulder harness  28  and corresponding force-sensitive actuators  34  on each of the columns  16  and four restraint straps  32  also separated in a horizontal plane by 90 degrees, the plane being parallel to and below that of the shoulder harness  28 , and communicate between the hip harness  30  and corresponding force-sensitive actuators  34  on each of the columns  16 . 
         [0054]    Referring now to  FIG. 3 , each force-sensitive actuator  34  receives a restraint cord  36  leading from the restraint straps  32  which may pass through a follower arm  38  pivotally attached to an angle resolver  40 . The angle resolver  40  pivots about a vertical pivot axis so that the angle of force exerted by the patient  15  on the restraint strap  32  within a horizontal plane may be determined and provided to the computer/controller  26 . The cord  36  may then pass through a set of centering rollers  39  and in one embodiment may be fixedly attached with respect to the columns  16  or, as shown, may be received by a spool  41  driven by a force motor/resolver  42  allowing a computer-controlled force to be applied to the cord  36  and the extension of the cord  36  to be measured. In both cases of the cord  36  being fixed or attached to the spool  41 , the force between the cord  36  and the column  16  may be measured by means of a load cell  44  communicating with the computer/controller  26 . 
         [0055]    Referring now to  FIG. 4 , when the cord restraint strap  32  is fixedly attached to the columns  16 , it may include an elastic portion  46  that applies a restoring force to the patient  15  at all times when the patient is not properly vertically aligned. Restoring three is a nonlinear function of the extension of the elastic portion  46  which provides for some ability for the patient  15  to move during normal walking or experimentation with balance. Excessive leaning of the patient  15  from vertical will cause the elastic portion  46  to reach a stretch limit  48  where further extension of the elastic portion  46  is fully resisted by substantially inelastic cords of the restraint strap  32  providing an abrupt nonlinearity in the spring-biasing force and protecting the patient  15  from instability. 
         [0056]    Referring now to  FIG. 5 , each footplate  24  may generally be movable along stride axis  20  as discussed above, for example, communicating through the surface of the platform  14  by means of slots  50  to the underlying carriages  22  which may move to provide for stride-related motion of the footplates  24 . The patient&#39;s foot (not shown in  FIG. 5 ) may be received within a shoe  52 , for example, being a general-purpose walking or running athletic shoe roughly centered within the rectangular area of the footplate  24  and held by a harness  56  thereto. Generally the harness  56  will limit displacement of the patient&#39;s foot and shoe  52  along the stride axis  20  with respect to the center of the footplate  24 . That is, the harness  56  will prevent motion between the shoe  52  and the footplate  24  in the direction of the stride axis  20 . Nevertheless, the harness  56  will allow toe lift and heel lift (as described below), minor inversion and eversion of the foot and minor rotation about a vertical axis necessary for natural walking. 
         [0057]    The harness  56  is attached to a safety wire  58  that electrically communicates between a releasable electrical connector  60  at a front end  62  of the footplate  24  and a releasable electrical connector  64  at a rear end  66  of the footplate  24 . Excessive motion of the harness  56  will cause one of the connectors  60  and  64  to be disconnected thereby communicating a loss of electrical continuity to an alarm detector  68 . The alarm detector  68  may communicate with the computer/controller  26  such as may be used to stop motion of the footplates  24  or provide an alarm or the like. 
         [0058]    Referring now to  FIGS. 5, 6 and 7 , each harness  56  may generally include a toe portion  70  and a heel portion  72  that operate together to restrain a shoe  52  holding the foot of the patient  15 . The toe portion  70  may include a first U-shaped flexible strap  74  extending from a first attachment point  76   a  at a right side of the rear end  66  of the footplate  24  and looping around the toe of the shoe  52  to a second attachment point  76   b  at a left side of the rear end  66  of the footplate  24 . The strap  74  may be attached at the attachment points  76  by means of inter-engaging hook and loop fasteners, different portions situated on different ones of the strap  74  footplate  24 . These hook and loop fasteners are more resistant to shear forces (and thus help stabilize the position of the shoe  52  along the stride axis  20 ) but readily disconnect under normal force by the patient  15 , for example, if the patient  15  needs to rapidly reposition his or her foot for safety. 
         [0059]    The loop of the strap  74  proximate the toe of the shoe  52  is formed into a toe pocket  75  by means of an underlying strap  78  fitting under the toe of the shoe  52  and extending laterally to be attached at its left and right, ends to the strap  74  and an overlying strap  80  fitting over the toe of the shoe  52  also attached at its left and right ends to the strap  74 . The toe pocket  75  serves to attach the strap  74  to the toe of the shoe  52 . 
         [0060]    An apex of the loop formed by the strap  74  may attach to left and right rearwardly extending shoe retention straps  82  terminating in adjustable buckles  84  of a type known in the art. Each of the straps  78  and  82  may also be constructed of the same material as strap  74  (for example, a nylon webbing) and assembled together by stitching. 
         [0061]    The heel portion  72  may include a single medial flexible strap  86  extending from a third attachment point  76   c  at a front end  62  of the footplate  24  centered between the left and right edges of the footplate  24 . The strap  86  may be attached at the attachment point  76   c  by means of inter-engaging hook and loop fasteners, one on the end of the strap  86  and the other fixed to the footplate  24  as discussed above. 
         [0062]    The remaining end of the medial flexible strap  86  attaches to the heel of the shoe  52  by means of a heel pocket  88  formed by a U-shaped heel strap  90  attached at its center to an unattached end of medial strap  86  and curving about the heel of the shoe  52  and forward, to terminate at buckle portions  92  receivable by buckles  84 . The end of the strap  86  proximate to the heel attaches at its center to laterally extending strap  94  fitting beneath the heel of the shoe  52  to be attached to strap  90  at its opposite ends thereby completing the heel pocket  88 . 
         [0063]    Each of the straps  86 ,  90 ,  94  may also be constructed of the same material as strap  74  and assembled together by stitching. 
         [0064]    Adjustment of the length of the straps  82  through the buckles  84  allows the toe pocket  75  and heel pocket  88  to be drawn together about the shoe  52  to prevent substantial slippage between the shoe and the harness  54 . As so assembled, the medial flexible strap  86  is generally centered between the opposed arms of strap  74  to prevent interference between the strap  74  and  86 . 
         [0065]    Referring now to  FIG. 8 , during a normal stride by the patient  15 , when the footplate  24  is in a forward position and the patient&#39;s leg extended forwardly, the patient&#39;s heel may be against the footplate  24  and the toe elevated. At this time both strap  74  and strap  86  may be substantially without slack (in slight tension) to prevent forward or backward movement of the toe of the shoe  52  with respect to the footplate  24 . Toe and heel lifting is possible based on the geometry of the straps; however, motion in the direction of the stride axis  20  is largely resisted by the routing of the straps below the foot and the shallow angle of straps  74  and  86  and the close proximity of the attachment points  76   c  and  76   a  and  76   b  along the stride axis  20 . Little or no strap elasticity is required. Generally the axial separation  77  of the attachment points of the straps  74  and  86  to the shoe  52  will be more than half the axial separation  79  of the attachment points of the straps  74  and  86  to the footplate  24 . Note that the strap  74  may be in part trapped beneath the heel of the shoe  52  further serving to limit axial movement of the shoe  52  with respect to the footplate  24  and to preserve tension in the straps  74  and  86   
         [0066]    As the footplate  24  moves rearwardly, the shoe  52  in a normal stride will arrive to lie flat against the upper surface of the footplate  24  with neither the heel nor toe elevated as shown in  FIG. 9 . In this position, minor tension on the straps  74  and  86  continues to hold the relative location of the foot with respect to the footplate  24 . 
         [0067]    Finally, as shown in  FIG. 10  when the footplate  24  is in the rearmost position, the heel of the shoe  52  may rise as is permitted by the geometry of the attachment of the straps  86  and  74  while still providing slight tension between the toe along strap  74  and the attachment point  76  and the heel along strap  86  with attachment point  76   c  still preserving relative fixation of the shoe  52  with respect to the footplate  24 . In contrast to  FIG. 8 , here the strap  86  may be in part trapped beneath the toe of the shoe  52  preventing slack in the straps  76  and  74  and providing improved localization of the shoe  52 . 
         [0068]    Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context. 
         [0069]    When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
         [0070]    References to “a controller” can be understood to include one or more microprocessors that can communicate in a stand-alone and/or a distributed environment(s), and can thus be configured to communicate via wired or wireless communications with other processors, where such one or more processor can be configured to operate on one or more processor-controlled devices that can be similar or different devices. Furthermore, references to memory, unless otherwise specified, can include one or more processor-readable and accessible memory elements and/or components that can be internal to the processor-controlled device, external to the processor-controlled device, and can be accessed via a wired or wireless network. 
         [0071]    It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein and the claims should be understood to include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. All of the publications described herein, including patents and non-patent publications, are hereby incorporated herein by reference in their entireties.