Abstract:
An exoskeleton comprises a torso brace, configured to be coupled to a torso of a user, and a leg support, configured to be coupled to a leg of the user. A plurality of links couples the torso brace to the leg support. The plurality of links includes a first link, coupled to the torso brace at a first pivot point, and a second link, coupled to the leg support at a second pivot point. The first link is coupled to the second link through a third pivot point located between the first and second pivot points. The first pivot point enables adduction of the leg support, and the third pivot point enables abduction of the leg support.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/007,511, which was filed on Jun. 4, 2014 and titled “Collocated Exoskeleton Hip Abduction Joints”. The entire content of this application is incorporated by reference. 
     
    
     GOVERNMENT LICENSE RIGHTS 
       [0002]    This invention was made with government support under Contract H92222-14-9-0001 awarded by the United States Special Operations Command. The government has certain rights in the invention. 
     
    
     FIELD OF THE OF THE INVENTION 
       [0003]    The present invention relates to a device and method that augments a user&#39;s carrying capacity and strength, increasing performance and aiding in the prevention of injury during the execution of certain load-bearing or strength-requiring tasks. More particularly, the present invention relates to a device suitable for use by a person engaging in weight-bearing tasks, the device comprising a set of artificial limbs and related control systems that potentiate improved function of the user&#39;s appendages including, but not limited to, greater strength and endurance in the user&#39;s legs, allowing for more weight to be carried by the user while walking. 
       BACKGROUND OF THE INVENTION 
       [0004]    Wearable exoskeletons have been designed for medical, commercial and military applications. Medical exoskeletons are designed to help restore a user&#39;s mobility. Commercial and military exoskeletons help prevent injury and augment a user&#39;s stamina and strength by alleviating loads supported by workers or soldiers during strenuous activities. Exoskeletons designed for use by able-bodied users often act to improve the user&#39;s stamina by transferring the weight of a tool or load through the exoskeleton structure and to the ground, thus decreasing the weight borne by the user. For the exoskeleton to transfer this weight to the ground, each exoskeleton support member and exoskeleton joint between the exoskeleton weight and the ground must be able to act as a conduit of this force around the user. This requires a degree of rigidity, seen in the joints of current exoskeletons, that can limit the range of motion of some exoskeleton joints. By limiting the flexibility at these joints, the mobility and maneuverability of the exoskeleton is reduced, thereby limiting the usefulness of the exoskeleton in certain applications. 
         [0005]    Supporting the structure of an exoskeleton through a hip joint while maintaining a high degree of hip joint flexibility is one of the more difficult exoskeleton design challenges. In order to transfer weight effectively at the hip joint, many current exoskeleton designs utilize a hip joint with limited flexibility, particularly with respect to hip abduction and adduction. The flexibility of the hip of some exoskeleton designs is improved by adding an array of joints and movable members that extend away from the hip joint of the exoskeleton user. Such designs, in which the exoskeleton structure extends substantially away from the body of the exoskeleton user, result in a high level of relative movement between the exoskeleton legs and hips and the legs and hips of the user during some leg and hip movements. Differences in relative movement are undesirable for a number of reasons: they make exoskeleton movements less like the human movements that are intuitive to the exoskeleton user; and, importantly, they can result in translational movements at the legs that cause chafing between the user and the exoskeleton. Preventing this translational movement requires additional exoskeleton design features to allow the exoskeleton legs to extend or compress in order to maintain the same length as the user&#39;s legs. In addition, the added bulk of hip joints that extend away from the user can decrease exoskeleton maneuverability in tight spaces, increase exoskeleton weight and interfere with the motion of the exoskeleton user&#39;s arms. 
         [0006]    Due to the limitations imposed on exoskeleton use by the restricted range of motion in exoskeleton hip joints, there exists a need in the art to develop a device that allows improved flexibility in weight-bearing exoskeleton hip joints. There exists a further need to develop joints in which the relative movement between the exoskeleton and the exoskeleton user is minimized and to develop joints that do not substantially increasing the bulk of the exoskeleton at the hip joints. 
       SUMMARY OF THE INVENTION 
       [0007]    Disclosed herein are devices and methods that allow for greatly improved flexibility in weight-bearing exoskeleton hip joints. The exoskeleton hip joints are collocated with the hip joints of a user, thus keeping the structural pieces closely fit to the body of the user and forming more biomechanically equivalent exoskeleton hip joints. This results in decreased relative movement between the exoskeleton and user. 
         [0008]    In particular, the present invention is directed to an exoskeleton comprising a torso brace, configured to be coupled to a torso of a user, and a leg support, configured to be coupled to a leg of the user. A plurality of links couples the torso brace to the leg support. The plurality of links includes a first link, coupled to the torso brace at a first pivot point, and a second link, coupled to the leg support at a second pivot point. The first link is coupled to the second link through a third pivot point located between the first and second pivot points. The first pivot point enables adduction of the leg support, and the third pivot point enables abduction of the leg support. The exoskeleton is configured to transfer at least a portion of the weight of a load from the torso brace, through the plurality of links and to the leg support. 
         [0009]    In one embodiment, an axis of rotation of the third pivot point is generally perpendicular to both an axis of rotation of the second pivot point and a coronal plane of the exoskeleton. An axis of rotation of the first pivot point is generally parallel to the axis of rotation of the third pivot point. 
         [0010]    In another embodiment, the second link is directly coupled to the first link at the third pivot point, or the second link is directly coupled to a third link, of the plurality of links, at the third pivot point. In one embodiment in which the second link is coupled to the third link, the first link is also directly coupled to the third link. 
         [0011]    In yet another embodiment, the first and second links are configured to make physical contact during adduction of the leg support, thereby limiting adduction of the leg support. A strap is coupled to the first link, and the strap is configured to limit movement of the first link relative to the torso brace. A second plurality of links couples the torso brace to a second leg support, the second plurality of links including a first link coupled to the torso brace at a first pivot point. The strap couples the first link of the first plurality of links to the first link of the second plurality of links. 
         [0012]    Additional objects, features and advantages of the invention will become more readily apparent from the following detailed description of preferred embodiments thereof when taken in conjunction with the drawings wherein like reference numerals refer to common parts in the several views. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1A  is a rear view of an exoskeleton constructed in accordance with a primary embodiment of the present invention; 
           [0014]      FIG. 1B  is a side view of the exoskeleton of the primary embodiment; 
           [0015]      FIG. 1C  is a front view of the exoskeleton of the primary embodiment; 
           [0016]      FIG. 2A  is a rear view of a hip joint of the primary embodiment in a neutral hip position; 
           [0017]      FIG. 2B  is a rear view of the hip joint of the primary embodiment and demonstrates movement of a right hip in maximum abduction while a left hip is in the neutral position; 
           [0018]      FIG. 2C  is a rear view of the hip joint of the primary embodiment and demonstrates movement of the right hip in maximum adduction while the left hip is in the neutral position; 
           [0019]      FIG. 3A  is a rear view of the exoskeleton of the primary embodiment and demonstrates abduction at a hip joint of a user&#39;s right leg; and 
           [0020]      FIG. 3B  is a rear view of the exoskeleton of the primary embodiment and demonstrates adduction at hip joints of both of the user&#39;s legs. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    Detailed embodiments of the present invention are disclosed herein. However, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale, and some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to employ the present invention. Additionally, as used in connection with the present invention, terms such as “parallel” and “perpendicular” do not necessarily require, for example, that the relevant items be perfectly parallel. Instead, these terms contemplate a margin of error of +/−5° (regardless of whether the error is by design or due to inherent manufacturing limitations) so long as the error does not prevent the present invention from functioning as intended. The modifier “substantially” increases the margin of error to +/−10°, while the modifier “generally” increases the margin to +/−15°. 
         [0022]    In the present invention, exoskeleton hip joint flexibility is improved through the incorporation of at least one additional rotatable member in the coronal plane of the hip joint structure of the exoskeleton (relative to previous designs). This rotatable member is prevented from moving in the adduction direction medial of normal stance. Incorporation of this hip joint device provides for a greater degree of freedom and flexibility in the affected hip joint without compromising the ability of the affected hip joint to bear weight. 
         [0023]    The primary embodiment of the present invention comprises an exoskeleton hip joint device with two rotatably connected members that are rotatable in the coronal plane. The rotatable members attach the exoskeleton leg to the exoskeleton torso in such a way as to allow the exoskeleton structure to abduct and adduct the exoskeleton leg. The exoskeleton hip is collocated with and closely fit to the hip of the exoskeleton user, thus forming a more biomechanically equivalent exoskeleton hip joint. The hip joint device also has hard stops restricting movement of these rotatable connected members, particularly to prevent the joint from moving in the adduction direction of the leg upon which the exoskeleton is standing when the exoskeleton is standing on one leg. This is important so as to allow the exoskeleton to transfer the load of the exoskeleton (and any other attached load) through the exoskeleton hip while standing on the corresponding leg. 
         [0024]    With reference to  FIGS. 1A-C , a user  100  is shown wearing an exoskeleton  105  having a hip joint  110 . Hip joint  110  supports the weight of a rear exoskeleton structure  115 , which is connected to a torso brace  120 . An upper rotatable link  125  is rotatably connected to torso brace  120  by an upper rotor  130  (at an upper pivot point), which applies spring tension to upper link  125  in the abduction direction relative to torso brace  120 . Abduction of upper link  125  is limited by tension applied by an adjustable restraining strap  135 , which is connected to an opposing upper rotatable link  126 . An extension link  140  is connected to upper link  125 , and a lower rotatable link  145  is rotatably connected to extension link  140  by a lower rotor  150  (at a lower pivot point). In some embodiments, extension link  140  and upper link  125  are the same link i.e., integral; similarly, in some embodiments, extension link  141  and upper link  126  are the same link. Lower link  145  is connected to a leg support  155  by a hinge joint  160  (at a leg pivot point), and leg support  155  is coupled to a leg  165  of user  100  by braces  170  and  171  and a boot  175 . Leg support  155  is also connected to boot  175 , which contacts a surface  180 . As a result of the above-described structure, the weight of a load (e.g., rear exoskeleton structure  115  or an object attached thereto) is transferred to surface  180  through torso brace  120 , upper link  125 , link extension  140 , lower link  145 , leg support  155  and boot  175 . Since the structure of exoskeleton  105  can take various forms, as is known in the art, the portions of exoskeleton  105  unrelated to the present invention will not be detailed further herein. 
         [0025]    Turning to  FIG. 2A , hip joint  110  is shown in the neutral position, i.e., with no adduction or abduction of either leg. As discussed above, upper link  125  is rotatably connected to torso brace  120  by upper rotor  130 , which applies spring tension to upper link  125  in the abduction direction. Abduction of upper link  125  is limited by tension applied by strap  135 , which is connected to opposing upper link  126 . Upper link  126  is connected to torso brace  120  by an opposing upper rotor  131 , and upper rotor  131  applies spring tension to upper link  126  in the abduction direction relative to torso brace  120 . As a result, strap  135  prevents either of upper rotor  130  or upper rotor  131  from rotating in the abduction direction without a corresponding rotation in the adduction direction by the other rotor (i.e., on the opposite side of hip joint  110 ). Extension link  140  is connected to the upper link  125 , and lower link  145  is rotatably connected to extension link  140  by lower rotor  150 . Extension link  140  serves to position upper link  125  and lower link  145  in such a way that adduction of the lower link  145  is limited by a physical clash with upper link  125  in the coronal plane of exoskeleton  105 , thus preventing adduction of lower link  145  beyond the position shown in  FIG. 2A . Limiting the maximum adduction of lower link  145 , and, therefore, limiting the maximum adduction of leg support  155 , is important for the exoskeleton being able to bear a load during the stance phase. Without an adduction stop, the moment generated by the load bearing on torso brace  120  would need to be supported by user  100 , thereby making user  100  bear the vertical weight of the load as well and rendering exoskeleton  105  incapable of bearing the load as intended. By designing upper link  125 , extension link  140  and lower link  145  so that adduction about lower rotor  150  is stopped at an adduction angle that is typical during walking, exoskeleton  105  will bear the moment and then the load as well. 
         [0026]      FIG. 2B  shows hip joint  110  with the left leg in the neutral position and the right leg in abduction. Lower link  145  is shown rotating about lower rotor  150  and abducting relative to torso brace  120 . The maximum abduction of lower link  145 , which extends behind the plane of this drawing as shown in  FIG. 1B , is limited by contact with torso brace  120 . It should be noted that the abduction of leg support  155  of exoskeleton  105  occurs only through rotation of lower link  145  about lower rotor  150  and without rotation by either of upper rotor  130  or upper rotor  131 , which allows abduction of leg support  155  while exoskeleton  105  is standing on an opposing leg support  156 . 
         [0027]      FIG. 2C  shows hip joint  100  with the left leg in the neutral position and the right leg in adduction. As discussed above, upper rotor  130  applies spring tension to upper link  125  in the abduction direction. In  FIG. 2C , the spring force of upper rotor  130  is overcome by force from user  100  or exoskeleton  105  in order to move the right leg in adduction. Specifically, upper link  125  is moved in the adduction direction about upper rotor  130 . During adduction, strap  135  becomes slack as upper link  125  draws nearer to upper link  126 . Continued adduction of upper link  125  is restrained by physical contact with upper link  126 . As both upper link  125  and upper link  126  move in the same plane, physical clashing limits maximal relative adduction for upper links  125  and  126 . It should be noted that the adduction of leg support  155  of exoskeleton  105  occurs only through rotation of upper link  125  about upper rotor  130  and without rotation by either lower rotor  150  or upper rotor  131 , which allows adduction of leg support  155  while exoskeleton  105  is standing on leg support  156 . 
         [0028]    With reference now to  FIG. 3A , lower link  145  is shown rotated in the coronal plane about lower rotor  150  in the abduction direction. As lower link  145  is connected to leg support  155  by hinge joint  160 , leg support  155  is abducted to the same extent as lower link  145  in terms of angle change in the coronal plane. Since leg support  155  and leg  165  are no longer in contact with surface  180 , hip joint  110  bears the weight of exoskeleton  105  and transfers this weight to leg support  156  (coupled to an opposing leg  166 ), which ultimately transfers the weight of exoskeleton  105  to an opposing boot  176  and surface  180 . 
         [0029]      FIG. 3B  shows upper links  125  and  126  rotated in the adduction direction about upper rotors  130  and  131 , respectively. Strap  135  is slack and applies no significant force to upper links  125  and  126 . Leg supports  155  and  156  are adducted to the same angle in the coronal plane as upper links  125  and  126 , respectively. This adduction results in a crossing of legs  165  and  166 , while leg supports  155  and  156 , which are connected to boots  175  and  176 , transmit the weight of exoskeleton  105  to surface  180 . It should be noted that lower link  145  and an opposing lower link  146  do not rotate about lower rotor  150  and an opposing lower rotor  151  during adduction of leg supports  155  and  156  because the hard stops (described above in connection with  FIGS. 2A and 2C ) prevent such adduction motion. 
         [0030]    Based on the figures and the above discussion, it can be seen that the axes of rotation of rotors  150 ,  151  are at least generally perpendicular to: 1) the axes of rotation of rotors  160 ,  161 ; and 2) the coronal plane of exoskeleton  105 . Additionally, the axes of rotation of rotors  130 ,  131  are at least generally parallel to the axes of rotation of rotors  150 ,  151 . Preferably, these axes of rotation are substantially perpendicular or parallel and, more preferably, perpendicular or parallel. 
         [0031]    As an example of the primary embodiment, consider a soldier wearing an exoskeleton and navigating through rough terrain. The improved flexibility of the hip joints allows the soldier to select a path with obstacles that would restrict a user wearing a prior art exoskeleton design. For instance, abduction at the hip joint, as shown in  FIG. 3A , allows the exoskeleton and soldier to more easily walk along sloped or uneven surfaces. Yet at the same time, the exoskeleton will bear the weight of the exoskeleton and a payload attached to the exoskeleton, thereby providing the parallel load path that is a goal of the exoskeleton. The ability to adduct both legs, as shown in  FIG. 3B , even crossing them over while walking or standing, allows the exoskeleton and soldier to walk through more narrow spaces (e.g., between obstacles or over a narrow surface) and also allows the exoskeleton and user to turn more quickly, thereby improving maneuverability in tight spaces. 
         [0032]    The exoskeleton of the primary embodiment, due to the improved biomechanical equivalence resulting from collocating the hip structure close to the body of the user, permits abduction with less resistance than the abduction hinge joint disclosed in U.S. Pat. No. 7,947,004 in which the hinge is beside the user&#39;s hip. This is because, in the exoskeleton of the primary embodiment, there is no resistance from a spring system designed to take up translation resulting from a non-collocation of the axis of rotation, as in the prior art. 
         [0033]    In some embodiments, the exoskeleton has at least one actuated joint. In other embodiments, the exoskeleton joints are not actuated. Optionally, in place of lower rotor  150 , a plurality of pivot points can be provided between upper rotor  130  and hinge pivot  160 , for example. Also, in some embodiments, there is an additional abduction hinge joint located below the joint of the primary embodiment of the present invention. This additional hinge joint, disclosed in U.S. Pat. No. 7,947,004, which is incorporated herein in its entirety by reference, can work in concert with the joint of the primary embodiment to improve the flexibility of an exoskeleton hip in the coronal plane, specifically by allowing for abduction of a leg when the leg is under flexion. In other embodiments, additional joints are combined with the joint of the primary embodiment of the present invention (either alone or in combination with the hinge joint disclosed in U.S. Pat. No. 7,947,004). These additional joints include members that allow for rotation of the leg and one or more compression-elongation mechanisms, which allow for lengthening of the leg structure relative to the hip and knee joints. The compression-elongation mechanisms are used to take up translation resulting from non-collocation of the axis of rotation caused by abduction at the hinge joint, as disclosed in U.S. Pat. No. 7,947,004. These rotational joints and compression-elongation mechanisms are also disclosed in U.S. Pat. No. 7,947,004. 
         [0034]    Based on the above, it should be readily apparent that the present invention provides a device and method that enables improved flexibility in weight-bearing exoskeleton hip joints. Although described with reference to preferred embodiments, it should be readily understood that various changes or modifications could be made to the invention without departing from the spirit thereof. In general, the invention is only intended to be limited by the scope of the following claims.