Machine to human interfaces for communication from a lower extremity orthotic

A lower extremity orthosis is configured to be coupled to across at least one joint of a person for gait assistance and can incorporate knee, thigh, hip and ankle/foot assistive orthotic devices which can be used in various combinations to aid in the rehabilitation and restoration of muscular function in patients with impaired muscular function or control.

BACKGROUND OF THE INVENTION

The present invention relates to orthotic devices that aid in the rehabilitation and restoration of muscular function in patients with impaired muscular function or control. More particularly, the present invention relates to orthotic devices and configurations of these orthotic devices suitable for therapeutic use with patients that have impaired neuromuscular/muscular function of the appendages, including, but not limited to, orthotic devices including of a motorized system of braces and related control systems that potentiate improved function of the appendages for activities such as walking.

Millions of individuals suffer from either partial or total loss of walking ability, resulting in greatly impaired mobility for the afflicted individual. This disabled state can result from traumatic injury, stroke, or other medical conditions that cause disorders that affect muscular control. Regardless of origin, the onset and continuance of walking impairment can result in additional negative physical and/or psychological outcomes for the stricken individual. In order to improve the health and quality of life of patients with walking impairment, the development of devices and methods that can improve or restore walking function is of significant utility to the medical and therapeutic communities. Beyond walking impairment, there are a range of medical conditions that interfere with muscular control of the appendages, resulting in loss of function and other adverse conditions for the affected individual. The development of devices and methods to improve or restore these additional functions is also of great interest to the medical and therapeutic communities.

Human exoskeleton devices are being developed in the medical field to restore and rehabilitate proper muscle function for people with disorders that affect muscle control. These exoskeleton devices can be represented as a system of motorized braces that can apply forces to the wearer's appendages. In a rehabilitation setting, exoskeletons are controlled by a physical therapist and/or the patient wearing the exoskeleton who uses one of a plurality of possible inputs to command an exoskeleton control system. In turn, the exoskeleton control system actuates the position of the motorized braces, resulting in the application of force to, and typically movement of, the body of the exoskeleton wearer.

Exoskeleton control systems prescribe and control trajectories in the joints of an exoskeleton. These trajectories can be prescribed as position based, force based, or a combination of both methodologies, such as those seen in an impedance controller. Position based control systems can modify exoskeleton trajectories directly through modification of the prescribed positions. Force based control systems can modify exoskeleton trajectories through modification of the prescribed force profiles. Complicated exoskeleton movements, such as walking, are commanded by an exoskeleton control system through the use of a series of exoskeleton trajectories, with increasingly complicated exoskeleton movements requiring an increasingly complicated series of exoskeleton trajectories. These series of trajectories may be cyclic, such as the exoskeleton taking a series of steps with each leg, or they may be discrete, such as an exoskeleton rising from a seated position into a standing position.

Depending on the particular physiology or rehabilitation stage of a patient, different degrees of assistance must be provided by the exoskeleton in various motions required for walking. For some patients, such as paraplegics, the actuators of a modern exoskeleton must provide all of the force required for walking. However, in some applications where a patient has some function, it may be sufficient to simply provide a push in the correct direction at the correct position in the gait cycle. This sort of locomotion assistance can be likened to pushing a child on a swing: the push provided need not be precise as long as it is neither so small that motion of the swing decays nor so large that the motion of the swing becomes unstable. Thus, it is possible for an exoskeleton to facilitate the walking of a patient by simply providing some assistance at a key portion of the gait cycle.

In people who have limited use of their lower limbs, restoring the function of the knee is critical to the restoration of standing or walking function because the leg cannot bear weight without a functioning knee. This is made clear within the field of prosthetics where the greatest effort and complexity of design is dedicated to the design of knee prostheses. Historically, knee prostheses were the first to incorporate microprocessors and later powered actuators as well. In the field of orthotics, conventional mechanical devices include braces that lock when the knee is straight and unlock in later stance so that the person can bend their knee during swing; these devices have been available for decades, although recent advances have rendered them smaller and more reliable. Newer orthotics, like prosthetics, have come to include microprocessors which allow for greater robustness to variable conditions. For example, in a traditional, purely mechanical orthosis, locking the knee for stance is triggered by reaching full knee extension in terminal swing. However, it may be desirable for the knee to lock in terminal swing even if the knee extension is not full, by using other markers such as looking for impact with the support surface using an accelerometer. Such behaviors are extremely difficult to design mechanically, but can be trivial to implement with a microprocessor. There are many examples of such devices known to the art, some of which are available for sale.

Existing knee orthosis devices have many shortcomings. Firstly, a stance control knee brace cannot provide active assistance to help a person go from sitting to standing. Some devices have the ability to power a person's gait. That is, in addition to having a microprocessor that can lock the knee at a fixed position, the device also has an actuator large enough to transfer mechanical power into the person's gait. The additional complexity required is non-trivial: the only actuation systems practical are electric motors using large (typically around 1:100) transmission ratios that convert the high speed, low torque motion of the motor into high torque, low speed motion needed for human locomotion. In some devices, this transmission is a ball screw device; in others a harmonic drive; and in others a hydraulic pump and cylinder. In all cases, there is a common difficulty besides the actuation, in that the device must be coupled to the person. Superficially, this may not appear to be a limiting factor since so many unpowered stance control knee braces have been designed, but in fact there is an important difference. Stance controlled knee braces are designed only to support body weight when the knee is nearly straight; in this situation, the torque resisted by the device is small. Powered knee braces can provide torque even when the knee angle is large, and are designed to produce very large torques often similar to those produced by the human body. In these cases, attempting to couple to the person is not a trivial problem, as the large torque generated by the device at the knee must be resolved through the person-device connection at both the thigh and the shank. This connection is typically soft, so as not to injure the person, and, as a result, applying high torque results in undesirable person-device motion. With this in mind, there exists an unmet need to provide a device by which a powered knee brace can exert sufficiently large forces on the knee of the person coupled to the knee brace so as to affect walking by the person coupled to the knee brace, while simultaneously decreasing relative motion between the person and the knee brace device. This device must also do so without producing undue discomfort or awkwardness to the patient coupled to the device.

An orthotic device with a powered knee brace alone can neither assist in the swinging of the leg, nor in the propulsion of the body during stance. Biomechanically, the hip plays a role in both functions, helping propel the person during stance and throw the leg forward during swing. While devices have been proposed to aid with the hip motion of the person during walking, these devices are cumbersome because they require high power actuation and/or close anthropomorphic coupling to the person. The human hip is a three degree of freedom joint, allowing motion in all three rotational axes; and while high powers for walking are required only in the sagittal plane, unpowered degrees of freedom must often be provided in the other axes in order to allow for normal walking. Some devices approximate these degrees of freedom with complex mechanisms, and others simply lock out these degrees of freedom, constraining the person. Therefore, an unmet need also exists to provide an orthotic hip device that allows assistance of leg movement in swing and propulsion of the body in stance, but without restricting degrees of freedom about the hip or requiring overly complicated, bulky, heavy mechanisms.

For some persons suffering from lower extremity weakness (often, but not always, post stroke), preventing foot drop is important, because otherwise the person may drag their toe on the ground, stumble, and fall. Therefore, an unmet need further exists to provide a device that is able to reliably lift the toe for the person during swing.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a lower extremity orthotic device that allows for a powered knee brace to exert sufficient force upon a person coupled to the powered knee brace so as to provide assistance to that person in both standing and walking, with this knee brace being capable of producing the very large torques similar to those produced by the human body during walking, but without these torques resulting in undesirable person-device motion. It is a further object of this invention that this powered knee brace device function without producing undue discomfort or awkwardness to the patient coupled to the device.

It is an additional object of the present invention for the lower extremity orthotic device to allow for an orthotic hip device to provide assistance to a coupled patient of leg movement in swing and propulsion of the body in stance, but without restricting degrees of freedom about the hip or requiring overly complicated, and often bulky, or heavy mechanisms.

It is a further object of the present invention for the lower extremity orthotic device to be able to reliably lift the toe of a person, who is wearing an orthosis or exoskeleton, during swing, in order to prevent that person from stumbling or falling.

The primary aspect of this invention comprises of a powered knee orthosis device that is not solely coupled to the person at their shank and thigh, with this device including lightweight spars, or other rigid linkages, that run from the actuation module up the length of the thigh to the hip, and down the shank to the ankle, with this device having small, unpowered pivots which are aligned, respectively, with the hip and ankle pivots of the person, with these connecting pivots being coupled to the hip and ankle of the person, respectively. As the couplings at the hip and ankle of the person are very distant from the knee, the forces reacted there are much less than when the orthosis forces are reacted at the shank and thigh, and therefore the motion between the person and the device is much less, allowing for the actuators powering the motion of the knee to provide more force.

The second aspect of this invention provides for a system that powers the hips of an exoskeleton through an actuation device positioned directly between the thighs, thus avoiding the complexity of a pelvic link and the need to provide for thigh rotation and abduction. In accordance with this aspect, the thighs of the person are coupled through an actuator so that the design need not couple around the person's pelvis. A variation of this embodiment allows higher torques with different packaging, in which the connection between hips is made from a location on the hip in line with the person's hip pivots.

The third aspect of this invention provides a passive mechanism that assists with the hip movement of a person wearing an exoskeleton device. In the simplest embodiment, a spring element is provided that engages during terminal stance, when the hip is very flexed, and thereby provides assistance during early swing.

The fourth aspect of this invention has the hips of a person wearing an exoskeleton to be coupled in such a way so that power is transferred from one hip to another. In accordance with this aspect of the invention, the hips are coupled through a motion reversing mechanism, such as a differential, so that when the right hip is moving backwards, the left hip is forced to move forwards. To be effective, the motion reversing mechanism must be grounded, and when it is grounded to the torso the resulting device is referred to as a reciprocating gait orthosis (RGO). In this embodiment, the motion between the RGO and the torso is controlled. By placing an actuator, in most embodiments, an electric motor with a speed reducing transmission, between the differential and the torso, the device can be made to behave like an RGO by locking the motor, or made to behave as if there is no RGO by applying zero torque, or in an intermediate state by controlling the motor to a torque profile.

The fifth aspect of this invention comprises of a lightweight orthotic device that pivots at the ankle of the leg fitted with the device, with an electromechanical brake arranged at the pivot. A sensor on the opposite leg of that bearing this pivot device detects foot contact with the ground and locks the rotation of the ankle of the leg fitted with the pivot and electromechanical brake. This brake holds the pivot and the ankle of the device wearer in dorsiflexion during swing. When the foot on the leg opposite the leg bearing this pivot device re-contacts the ground at the end of swing, the brake releases for a natural stance cycle. By adjusting the timing, the swing angle of the ankle may be varied. A variant of this embodiment comprises of a device that holds the ankle of a person wearing the device in dorsiflexion during swing, but without requiring an orthosis. In this embodiment, a cable connects between a strapping on the foot and the shank of the patient, with a retraction spring on the shank keeping this cable under tension, and a brake device that restricts the motion of the cable when the opposite leg strikes the ground, holding the ankle position of the leg bearing the device until the leg bearing this device strikes the ground.

Overall, these aspects of the invention can be synergistically combined to provide for overall enhanced functionality of the orthotic device in aiding in the rehabilitation and muscular function in patients with impaired muscular function or control. In any case, additional objects, features and advantages of the invention will become more readily apparent from the detailed description presented below, particularly when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is used in conjunction with powered or unpowered orthotic devices that provide for walking motion or assistance in walking motion(s) for the orthotic wearer. A powered exoskeleton is one example of such a powered orthotic device. In a rehabilitation setting, powered exoskeletons are controlled by a physical therapist who uses one of a plurality of possible input means to command an exoskeleton control system. In turn, the exoskeleton control system actuates the position of the motorized braces, resulting in the application of force to, and often movement of, the body of the exoskeleton wearer.

FIG. 1shows, for reference, a full body exoskeleton which is generally known to the art; this is done primarily to provide reference to various exoskeleton components that will be referred to in the application. With reference toFIG. 1, exoskeleton100having a trunk portion110and lower leg supports112is used in combination with a crutch102, including a lower, ground engaging tip101and a handle103, by a person or wearer109to walk. The wearer109is shown to have an upper arm111, a lower arm (forearm)122, a head123, and lower limbs124. In a manner known in the art, trunk portion110is configurable to be coupled to an upper body (not separately labeled) of the wearer109, the leg supports112are configurable to be coupled to the lower limbs124of the person109and actuators, generically indicated at125but actually interposed between portions of the leg supports112as well as between the leg supports112and trunk portion110in a manner widely known in the art, for shifting of the leg supports112relative to the trunk portion110to enable movement of the lower limbs124of the wearer109. In some embodiments, trunk portion110may be quite small and comprise a pelvic link wrapping around the pelvis of wearer109. In the example shown inFIG. 1, the exoskeleton actuators125are specifically shown as a hip actuator135which is used to move hip joint145in flexion and extension, and a knee actuator140which is used to move the knee joint150in flexion and extension. The exoskeleton actuators125are controlled by CPU120, with CPU120being a constituent of an exoskeleton control system, in a plurality of ways known to one skilled in the art of exoskeleton control. Although not shown inFIG. 1, various sensors in communication with CPU120are provided so that CPU120may monitor the orientation of the device. Such sensors may include, without restriction, encoders, inertial sensors, pressure sensors, potentiometers, accelerometers, and gyroscopes, with these sensors being located in various positions on the exoskeleton structure, depending on the needs of a specific exoskeleton or control system. In addition, CPU120is in either continuous or intermittent communication with, and reports all collected data to, a central server171. As the particular structure of various exoskeleton can take many forms, as is known in the art, the structure of this example exoskeleton will not be detailed further herein.

With reference toFIG. 2a, drawings representing a conventional powered knee orthosis device are shown. In the left panel ofFIG. 2a, a drawing of a conventional knee orthosis is shown. Person200is wearing a conventional knee orthosis201, with thigh structure203coupled to thigh202of person200, with thigh structure203being rotatably connected to knee joint204, with knee joint204being rotatably connected to shank structure206, with shank structure206being coupled to shank205of person200. Torque generator208is connected to both thigh structure203and knee joint204, with torque generator208exerting torque about knee joint204resulting in flexion or extension in the path of arrow207, with the rotation of knee joint204of orthosis201resulting in flexion or extension of the leg of person200by changing the relative angles of thigh202to shank205of person200. In the right panel ofFIG. 2a, a simple model of how the forces from a knee brace generating an assist torque are reacted onto the person. Here, the connection between person200and orthosis201is schematically represented as two patches, with thigh patch211being on thigh202of person200, and shank patch213being on the shank205of person200, with thigh patch211and shank patch213representing the strapping and/or cuffs that couple orthotic device201to person200. Thigh patch211and shank patch213must both react to the torque applied by torque generator208about the knee204, and as thigh patch length212and shank patch length214are relatively short, compared to the length of thigh202and shank205, the forces required for powered orthosis device to201to move thigh202relative to shank205is rather high, with extension resulting from forces215and216on thigh patch211and forces217and218on shank patch213, respectively. Although the forces are shown here as point loads on either edge of the strapping, it is understood that in well-designed strapping the force would be distributed, but simplifying to point loads does not change the nature of the problem with conventional powered knee orthoses; high knee torques result in undesirable relative motion between the person200and the orthosis201, as a result of compression of either the tissues of person200or the padding/strapping of orthosis201.

With reference toFIG. 2b, drawings representing the powered knee orthosis device of the primary embodiment of this invention are shown. The powered knee orthosis of the first embodiment is, using any appropriate actuation technique, coupled to the person in several places, in addition to their shank and thigh. Lightweight spars are run from the actuation module up the length of the thigh to the hip and down the shank to the ankle, as shown inFIG. 2b. At the hip and the ankle, small, unpowered pivots are provided, and these pivots are aligned, respectively, with the hip and ankle pivots of the person. In the left panel ofFIG. 2b, a drawing of the powered knee orthosis device of the primary embodiment is shown. Person220is wearing powered orthosis261, with orthosis261being coupled to the waist of person220by waist belt228, with waist belt228being rotatably connected to thigh link230by waist link229, with thigh link230being connected to thigh structure223, with thigh structure223being coupled to thigh222of person220, with thigh link230being rotatably connected to knee joint224, with knee joint224being rotatably connected to shank link231, with shank link231being coupled to shank251of person220, with shank link231being rotatably connected to foot link232, with foot link232being connected to foot structure233, with foot234of person220being coupled to foot structure233. Torque generator240is connected to both thigh link230and knee joint224, with torque generator240exerting torque about knee joint224resulting in flexion or extension in the path of arrow227, with the rotation of knee joint224of orthosis261resulting in flexion or extension of the leg of person220by changing the relative angles of thigh222to shank251of person220.

In the right panel ofFIG. 2b, a simple model of how the forces from a knee brace generating an assist torque are reacted onto the person. Here, the connection between person220and orthosis261is schematically represented as two patches, with thigh patch241being on thigh222of person220and shank patch243being on the shank251of person220, with thigh patch241and shank patch243representing the strapping and/or cuffs that couple orthotic device261to person220. Since knee joint224is connected to shank link231and thigh link230, which are connected to foot link232and waist link229, respectively, the torque from torque generator240is exerted over longer distances, thigh length242and shank length244, with extension resulting from force235on waist link229, force236on thigh patch241, force238on thigh patch238, and force237on foot link232.

In this first embodiment of this invention, the inclusion of the pivots at the hip and foot is a critical addition. In practice, the original strapping of lengths on the thigh and shank cannot be made longer because the person will find it uncomfortable to place strapping on the upper thigh or the lower shank; instead the pivots allow for the additional strapping to be located much farther from the knee, minimizing the forces. Furthermore, the waist belt acts near the center of mass of the person, and the foot strap acts near the reaction to the ground: the result is that the knee torque acts nearly directly between the center of mass and ground. As the couplings at the hip and ankle of the person are very distant from the knee, the forces reacted there are much less than when the orthosis forces are reacted at the shank and thigh, and therefore the motion between the person and the device is much less, allowing for the actuators powering the motion of the knee to provide more force. Yet, while such a design dramatically improves the function of the device, the complexity and cost of the additional structural component is not significant when compared to the actuation of the orthosis itself. In some embodiments, the orthosis is fitted with sensors, such as inertial sensors or pressure sensors, in various locations upon the orthosis that report information to an orthosis control system which controls the action of the torque generator on the orthosis, with these sensors reporting information on the orthosis state to the orthosis control system. In some embodiments, the torque generator is an electric motor, actuator, or other device known in the art.

In an example of the primary embodiment of this invention, consider a disabled patient in a rehabilitation setting who has limited strength in one leg. If this patient were to use the device of the invention, the orthosis would be able to provide additional knee torque to the patient, relative to the torque available by conventional powered orthoses, aiding this patient in knee motions related to walking and improving rehabilitative benefit.

With reference toFIGS. 3aand 3b, drawings representing one form of the powered thigh coupling orthosis device of a modified embodiment of this invention are shown. The human hip is a three degree of freedom joint, allowing motion in all three rotational axes. While the high powers for walking are required only in the sagittal plane, unpowered degrees of freedom must often be provided in the other axes in order to allow for normal walking. Some devices approximate these degrees of freedom with complex mechanisms, and others simply lock out these degrees of freedom, constraining the person. In this embodiment, the thighs of the person are coupled through an actuator so that the design need not couple around the person's pelvis. Person300is wearing thigh coupling orthosis301, with left thigh segment or structure303being coupled to the thigh of left leg302of person300, and with right thigh segment or structure305being coupled to the right thigh of person300. Left thigh structure303contains electric motor306, while right thigh structure305contains batteries and electronics311. Motor306connects to a universal joint307, with universal joint307being rotatably connected to a sliding spline308, with sliding spline308being rotatably connected to a universal joint309, with universal joint309being connected to mount310on right thigh structure305such that an actuator link is established between right and left thigh structures303and305. Torque generated in motor306is reacted directly in thigh segment305; as thigh segments303and305are coupled to the thighs of person300, the thighs of person300are driven equally and oppositely with the torque generated by motor306, resulting in either flexion350or extension351of leg304of person300. In other words, a single actuator is used to drive the right and left thigh structures303and305in opposite directions, e.g., one in an anterior direction and one in a posterior direction. Of course, in most embodiments, motor306will also comprise a transmission to generate a high torque, low speed motion appropriate to walking. Thigh segments303and305are coupled only to the thighs of person300, and as a result the device cannot produce large torques (because the forces applied to react the torque to the thighs will be unacceptably high; consider the first embodiment). Still, at the human hip joint, a modest torque of only 10 to 20 Newton-meters can produce a significant effect and result in a better gait for a person needing assistance and this torque can be applied at the thighs just as well as the hips. This design is further advantageous over existing devices because only one motor or actuator is required, simplifying the design of the device. In some embodiments, the electronics and batteries may be on the same side as the motor so that all the electrical elements are collocated, although this has the disadvantage that the weight is not evenly distributed. In some embodiments, the orthosis is fitted with additional sensors, such as inertial sensors, e.g., accelerometers and gyroscopes, in various locations upon the orthosis that report information to an orthosis control system which controls the action of the torque generator on the orthosis, with these sensors reporting information on the orthosis state to the orthosis control system. In some embodiments, inertial sensors, and even the control system, may be part of electronics311so that the complexity of the device is minimized, or may be included in both thigh structures303and305to capture motion information from both legs. In some embodiments, the torque generator is an electric motor, actuator, or other device known in the art.

With reference toFIG. 4, the drawings represent a variation of the overall powered thigh coupling orthosis device of the invention. This variation allows higher torques with different packaging. In this embodiment, the connection between the hips is made from a location on the hip in line with the person's hip pivots. As a result, the universal joints and spline are not needed. With reference toFIG. 4, person400with left thigh409and right thigh403is wearing device401. The device is comprised of right link404, actuator405, and left link407. Right link404is coupled to right thigh403with right thigh structure402, and left link407is coupled to left thigh409with left thigh structure408. Right and left links404and407are coupled through actuator405, rotating concentrically about hip pivot406. Hip pivot406is in line roughly with the centers of rotation of the hips of person400. Actuator405torques left link407with respect to right link404. Actuator405may be generally held onto the torso of person400with additional strapping that is not shown, but this strapping does not apply torque to the torso with respect to either thigh link. In operation, a controller causes actuator405to provide torque while person400is walking. The torque provided by actuator400acts directly between the legs of the person, resulting in either flexion450or extension451of leg410of person400, assisting in their walking. It is understood that the device could operate equally well with the opposite configuration, i.e., actuator406could instead be attached to the left hip with appropriately redesigned interconnecting links. Finally, the connection between the proximal end of left link407and actuator405can incorporate passive (unpowered) degrees of freedom in axes other than that of hip pivot406, allowing for normal motion of the thighs. Furthermore, left link407may be behind the person rather than in front, but in either case extends across the person to interconnect the right and left thigh structures402and408. In some embodiments, the chirality of the invention may be revered, with the actuator on the left side and the right and left links reversed.

The devices of this embodiment allows torque to be provided directly from one thigh to another. In either of these embodiments, a typical torque profile with respect to stance phases is shown inFIG. 5a. This profile provides a propulsive torque, shown on the Y axis500, versus time, shown on the X axis501, with trace502representing actuator torque during stance, and assists in throwing the leg forward during swing. Periods of right leg stance are shown as504,506, and505, while periods of left leg stance are shown as503,505, and507, with a left leg swinging step shown as510, and a right leg swinging step shown as511. In some embodiments, there may be a series elastic element between the legs so that the elastic element stores energy during double stance and releases that energy as the swing leg leaves the ground.FIG. 5bshows an additional embodiment of this controller that does not need foot sensors, and can be implemented simply using the thigh angular rates based on a MEMS gyroscope that may be included in the orthosis. RegardingFIG. 5b, actuator torque is plotted on Y-axis562, while time is plotted on X-axis561, with actuator torque trace563being plotted such that positive actuator torques extend the right hip and flex the left hip, while negative actuator torques flex the right hip and extend the left hip. Y axis564shows hip angular rate in degrees per second, with X-axis562in time, where the angular rate of right leg410is shown as solid trace565, while the angular rate of left leg409is shown as dashed trace566, and interstep cycle spacing is marked by dotted lines567. As shown, the stance phase is assumed to start when the thigh angular velocity is zero after it has been large and positive. Of course, the stance phase could start slightly earlier or later by looking for, respectively, a thigh rate that is slightly positive or negative rather than zero.

In an example of theFIGS. 3aand 3bembodiment of this invention, consider a disabled patient in a rehabilitation setting who has limited strength in both legs, and specifically limited strength in the hips. If this patient were to use the device of this embodiment, the orthosis would be able to provide additional hip torque to the patient, aiding this patient in knee motions related to walking and improving rehabilitative benefit.

With reference toFIG. 6a, a drawing representing the passive hip assistive device of a third embodiment is shown. Person600is wearing orthosis601, with waist belt or link603being coupled to waist604of person600, with hip support606being connected to waist belt603, with hip support606being rotatably connected to hip link607establishing a hip joint, with hip link607being connected to thigh support or link608, with thigh support608being connected to thigh structure609, with thigh structure609being coupled to leg610of person600. Hip support606is connected to an actuator, specifically in the form of a spring resilient element, such as a leaf spring612. Thigh support608is connected to spring stop611. Hip link607is aligned with the hip of person600. At small hip flexion angles, i.e., when the thigh support608is approximately posterior of vertical, leaf spring612engages spring stop611and generates hip torque; at large angles leaf spring612disengages from stop611and produces no hip torque. With this arrangement, the spring resilient element advantageously generates torque in the hip flexion direction during late stance and early swing. The actual abutment location can be adjusted, such as by repositioning or changing the slope of stop611. In some embodiments, the hip of the orthosis has additional features enabling abduction and rotation, such as those disclosed in FIG. 12 of U.S. Pat. No. 7,947,004 which is incorporated herein by reference. In some embodiments, the orthosis is fitted with sensors, such as inertial sensors or pressure sensors, in various locations upon the orthosis that report information to an orthosis control system which controls the action of the torque generator on the orthosis, with these sensors reporting information on the orthosis state to the orthosis control system. In some embodiments, the torque generator is an electric motor, actuator, or other device known in the art.

With reference toFIG. 6b, a plot showing hip gait data representing theFIG. 6aarrangement is shown. Human gait data that has been plotted parametrically for one step as hip angle versus hip torque, with torque plotted on the X-axis620and angle plotted on the Y-axis621. Hip gait data is shown as a solid trace with open circles622, while overlaid spring data appears as a dashed line623, representing theFIG. 6aarrangement of this invention that assists in late stance and early swing, increasing (forward) hip angles650and decreasing (rearward) hip angles651are shown inFIG. 6a. Heel strike occurs at the far right of the plot, and time proceeds counter clockwise; the large torques at the top of the loop are stance, the far left of the plot is roughly toe-off, and the small negative torques are swing. The hip torque/angle relationship can be approximated by a line in this region, and that line can be realized with a spring that disengages above a hip angle.

In an example of theFIG. 6aarrangement of this invention, consider a disabled patient in a rehabilitation setting who has limited strength in their legs who is engaged in physical therapy using an unpowered orthosis. If this patient were to use the device ofFIG. 6a, the patient will be provided assistance in the hip motions associated with walking, without requiring an orthosis powered at the hip or the related control systems.

With reference toFIG. 7, a drawing representing the powered reciprocating gait orthosis device of a modified form. In this embodiment, the device couple the hips of the person so that power is transferred from one hip to another. This embodiment has particular advantage for a patient exhibiting a hemiplegic strength deficit, that is, a strength deficit on only one side of their body. In this embodiment, the hips are coupled through a motion reversing mechanism such as a differential so that when the right hip is moving backwards, the left hip is forced to move forwards. To be effective, such as an aid in late stance and early swing, the motion reversing mechanism must be grounded, and when it is grounded to the torso, the resulting device can be referred to as a reciprocating gait orthosis (RGO). In this embodiment, the device is furthered by controlling the motion between the RGO and the torso. By placing an actuator (in most embodiments, an electric motor with a speed reducing transmission) between the differential and the torso, the device can be made to behave like an RGO by locking the motor, or made to behaving as if there is no RGO by applying zero torque, or in an intermediate state by controlling the motor to a torque profile. RegardingFIG. 7, person700is wearing RGO701, with waist brace or link702being coupled to waist703of person700, with rocker arm705being connected by pivot704to waist brace702, with actuator714applying force between rocker arm705and waist brace702resulting in rotation about pivot704. Rocker arm705is additionally rotatably connected to right thigh link706and left thigh link707, with right thigh link706being rotatably connected to right thigh mount708, with right thigh mount708being rotatably connected to a right thigh structure or segment710, with right thigh structure710being coupled to right thigh712of person700, and left thigh link707being connected to left thigh mount709, with left thigh mount709being rotatably coupled to a left thigh structure or segment711, with left thigh structure711being coupled to left thigh713of person700. Through RGO device701, forces from the movements of left thigh713of person700are transmitted to right thigh712of person700, with an actuator714selectively affecting the linked movements of and applying forces to left thigh713and right thigh712of person700. Actuator714can take various forms, including a powered actuator, a brake, or a resilient biasing member. In some embodiments, the orthosis is fitted with addition sensors, such as inertial sensors or pressure sensors, in various locations upon the orthosis that report information to an orthosis control system which controls the action of the torque generator on the orthosis, with these sensors reporting information on the orthosis state to the orthosis control system. In some embodiments, the actuator is placed in a different location, as actuation at any point on the orthosis can make use of the rocker arm to transfer force across the orthosis. In some embodiments, the RGO is not a rocker arm RGO, but is an RGO that uses cables or other means to transfer force across the orthosis. In some embodiments, it may be advantageous to instead place the actuator across only one of the left and right hip joints which allows power to be provided to both hip joints through the RGO.

In an example of this arrangement of this invention, consider a disabled patient in a rehabilitation setting. This RGO device has numerous advantages for use in a person with some function in one or both legs. First, when encountering an obstacle where the stiff gait imposed by an RGO will not work, freeing the motor (e.g., controlling it to zero current) effectively removes the RGO. As long as the patient has enough strength for a single step, they may disengage and reengage the RGO. Similarly, it allows a patient to sit in a chair while wearing the device. Second, the controller may allow the angle of the torso relative to the legs to change during the walking cycle, thereby making use of the RGO more comfortable and allow walking over varied terrain. Finally, in some embodiments, it may be desirable to vary the angle between the torso and the RGO body during a single gait cycle (i.e., continuously while walking) so that power is transferred to the person's gait cycle.

With reference toFIGS. 8aand 8b, an ankle and foot assistive orthotic device of the overall invention is shown. For some persons suffering from lower extremity weakness (often, but not always, post stroke), preventing foot drop is important, because otherwise the person may drag their toe on the ground, stumble, and fall. The goal for the device is to reliably lift the toe for the person during swing. The device may provide assistance with foot drop in two exemplary embodiments.FIG. 8aillustrates one embodiment in which lightweight orthotic pivoting at the ankle is provided, with an electromechanical brake arranged at the pivot, with person800wearing orthotic801, with orthotic801being coupled to right leg802of person800by thigh structure803and shank structure805, with foot808of person800being coupled to foot or heel structure807and stirrup815, with thigh structure803being rotatably connected to knee804, with knee804being rotatably connected to shank structure805and shank link806, with shank link806being rotatably connected to heel structure807. Brake813selectable locks the angle of shank link806relative to foot structure807, resulting in a lock of the angle of shank809of person800relative to foot808of person800. Brake813engages in locking when ground sensors811attached to foot structure816attached to the left leg817of person800detect contact between ground sensors811and surface810. In this way, the ankle of the right leg of person800is fixed in dorsiflexion during swing. When the foot808and foot structure807contact surface810at the end of swing, ground sensor815detects contact between foot structure807and surface810, signaling brake813to release and allowing the for a natural stance cycle for the right leg of person800. By adjusting the timing, the swing angle of the ankle may be varied. In some embodiments, other types of sensors are used to determine when the brake should be engaged. In some embodiments, the brake is some other type of selectably engaged locking mechanism, such as a locking pin or electric motor, or other device known in the art.

In an alternative embodiment shown inFIG. 8b, a device is shown that holds the ankle of a person wearing the device in dorsoflexion during swing, but without requiring a shank link. RegardingFIG. 8b, person840is wearing device821, with device821being coupled to right leg822of person840by ankle cuff805and foot828of person840by foot structure835. Foot structure835is connected to cable834, with cable834interacting with braking device833, with cable834being held is tension and connected to a retraction spring832or other retraction resilient element, with retraction spring832being connected to ankle cuff805. Housing structure837is connected to ankle cuff805and covers retraction spring832, and in some embodiments braking device833. The tension of retraction spring832is only strong enough to keep cable834in tension, but not strong enough to be noticeable by person840. Left leg817of person840is fitted with foot structure836, with ground sensor831being connected to foot structure836. Similarly to the previously discussed device ofFIG. 8a, when ground sensor831detects contact with surface810, braking device833engages and locks cable834in place, fixing the angle of ankle839. In this way, the ankle of the right leg of person800is fixed in dorsiflexion during swing. In some embodiments, when ground sensor835detects contact with surface810, braking device833releases cable834and allows ankle839to pivot. In another embodiment, braking device833is sized so that when leg822strikes the ground, braking device833does not produce enough force to hold cable834, allowing ankle839to pivot. This is possible because the force necessary at brake833to hold the foot828up during swing is much less than the force generated at braking device833by heel strike of foot828(and much more than the force at brake833produced by retraction spring832). In some embodiments, the cable is a chain, such as a bicycle chain, which might be engaged with various gearing mechanisms, including those attached to a braking device.

In an example of this arrangement, consider a patient in a rehabilitation setting who has recently suffered a stroke, and has problems with foot drag during gait on the stroke affected side. If this patient were to use this device, the device would be able to lift the affected foot of the patient during swing, preventing foot drag and possibly preventing injuries cause by a trip or fall related to foot drag.

In general, these various methods for assisting with hip motion and foot drop can be combined with various methods of stance control that are well understood in the art. Furthermore, the hip and foot methods may be combined with a powered knee brace using the device of the first embodiment design. For example, thigh element608of the hip spring mechanism inFIG. 6acould be the thigh link230from the powered knee brace ofFIG. 2b. In another embodiment, the thigh assistance device ofFIG. 4could be combined with the toe drop mechanism ofFIG. 8b. In some embodiments, the knee brace may not be powered, but may be one of a number of well understood devices that provide knee support during stance. Therefore, it should be realized that two or more of the knee, thigh, hip and ankle/foot assistive orthotic devices described above can be used in combination, actually producing synergistic results in aiding in the rehabilitation and restoration of muscular function in patients with impaired muscular function or control.