Passive exoskeleton

A load bearing apparatus is presented in the form of a passive exoskeleton whereby a load may be placed on the passive exoskeleton and thereby weight of the load from the passive exoskeleton is transferred to a ground surface. The passive exoskeleton is made of a rigid body member for attaching proximate a portion of a user's body; a sliding rod attached with the body member; a ground surface engage-able foot analog attached with the sliding rod; a rocker pivotally attached with the body member; a load pin attached with the sliding rod and operably attached with the rocker; and a bias block attached with the body member for engaging with the rocker. As a user walks, the bias block pivots the rocker to aid the load pin in transferring weight to the rocker and thereafter through the sliding rod to the foot analog and ground surface.

BACKGROUND OF INVENTION

(1) Field of Invention

The present invention relates to a load-bearing apparatus, and more particularly to a passive exoskeleton onto which a load may be placed, with the weight of the load transferred from the passive exoskeleton to a ground surface, causing the passive exoskeleton to support at least a portion of the load.

(2) Background of Invention

Load bearing devices have long been known in prior art. For example, backpacks with frames have long been employed to reduce a load carried by an individual's shoulders. Although the backpack functions to distribute the load, the weight of the load is transferred to the individual's hips, forcing the individual to ultimately bear the burden of the load. Because of the necessity to bear the burden of the load, the amount of weight an individual may carry using a traditional backpack is limited.

Other examples of load-bearing devices include orthopedic devices such as canes, crutches, and walkers. Although orthopedic devices transfer the load to the ground, they generally are designed under an assumption that the user must be able to stand and carry his/her own weight. Many orthopedic devices require the user's upper torso to be continuously used and such devices generally are not useful when upper limbs must remain free and unoccupied.

Another example of an orthopedic device is disclosed in U.S. Pat. No. 6,015,076, issued to Pennington (“the Pennington patent”). The Pennington patent discloses a hip belt which reduces fatigue by bridging across muscles and nerves in the gluteal region. A drawback of devices made according to this particular prior art is that all of the weight is still carried by the individual's skeletal and muscular system.

In an effort to reduce the load placed on the user's skeletal and muscular system, powered exoskeletons have been proposed. Powered exoskeletons mimic the function of body joints by using actuators or artificial muscles. The actuators required for these exoskeleton concepts consume significant power, supplies for which are either difficult to produce or are currently unavailable. Additionally, the compact actuator (artificial muscle) technology has currently not progressed enough to make practical devices. As such, the development of a powered exoskeleton requires further developments in a variety of fields, including actuation, artificial muscles, and advanced energy storage. Given the current state of these technologies, powered exoskeletons may not be realized for decades to come.

In an effort to provide an exoskeleton without a power system, the applicant of the present invention previously devised a passive exoskeleton. The passive exoskeleton comprises a rigid body member for attaching proximate a portion of a user's body, a rocker pivotally attached with the body member, a sliding rod attached with the rocker, and a ground surface engage-able foot analog attached with the sliding rod. The rocker has both a load channel and a travel channel, while a load pin attached with the sliding rod travels between the load and travel channels as a user walks. As a user places a load on the body member and walks forward, weight of the load is transferred from the body member, through the rocker's load channel, onto the load pin and its sliding rod. Thereafter, weight from the load passes into the foot analog, causing the passive exoskeleton to support at least a portion of the load. Rocker stops are attached with the body member, such that when a user is in a full stride gait, the rocker continues its motion until it hits the rocker stops at the limit of its travel. The rocker stops aid the load pin in transferring between the load and travel channels at the appropriate times during the user's forward gait. Although functional for forward motion, the problem with such a configuration is that it does not work as well for backwards (i.e., reverse) motion. With a single load channel, the rocker stops alone are not sufficient to aid in transferring the load pin between the load and travel channels when a user is traveling backwards.

Thus, it can be appreciated that there exists a continuing need for a passive exoskeleton that permits a user to walk both forward and backwards, such that in either direction, the load pin travels between the load and travel channels at the appropriate times during a user's gait. The present invention substantially fulfills this need.

SUMMARY OF INVENTION

The present invention relates to a load bearing apparatus, and more particularly, to a passive exoskeleton whereby a load may be placed on the passive exoskeleton and thereby transfer weight of the load from the passive exoskeleton to a ground surface.

The passive exoskeleton comprises a body member for attaching proximate a portion of a user's body; a sliding rod attached with the body member; a ground surface engage-able foot analog attached with the sliding rod; a rocker pivotally attached with the body member; a load pin attached with the sliding rod; and a bias block attached with the body member.

The rocker has a travel channel and a load channel incorporated therein. The travel channel is an elongated channel oriented directionally from proximate the body member to the ground surface. The load channel is formed as an elongated channel and positioned such that an angle between the load channel and the travel channel is less than ninety degrees. The rocker also includes a top component.

A load pin is attached with the sliding rod and operably attached with the rocker through both the travel channel and the load channel. The load pin is formed such that as a user walks and shifts from a swing phase to a stance phase, the load is transferred from the body member to the rocker, the shift causing the load pin to travel between the travel channel and the load channel.

A bias block is attached with the body member for engaging with the top component of the rocker. Both the bias block and the top component of the rocker are formed in such a manner such that as a user walks backwards and shifts between the swing phase and stance phase, the top component of the rocker passes a point of equilibrium where the bias block turns the rocker to aid the load pin in transferring between the load channel and travel channel, thereby shifting the load from the rocker onto the sliding rod and thereafter through the sliding rod to the foot analog and ultimately a ground surface, causing the passive exoskeleton to support at least a portion of the load.

In another aspect, the passive exoskeleton further comprises a pressure mechanism attached with the bias block for forcing the bias block against the top component of the rocker, thereby aiding the bias block in turning the rocker after the top component of the rocker passes the point of equilibrium. The pressure mechanism is selected from a group consisting of a spring and hydraulics.

The passive exoskeleton further comprises a neutral block attached with the passive exoskeleton. The neutral block is formed in such a manner that it is engage-able with the rocker to prevent the rocker from moving, such that when engaged with the rocker and when the load pin is in the travel channel, the load pin is maintained in the travel channel and is unable to transfer to the load channel, thereby causing the user to bear the full weight of the load.

In yet another aspect, the passive exoskeleton further comprises a front rocker stop and a rear rocker stop. The front rocker stop and the rear rocker stop are attached with the body member. Additionally, the rocker further comprises a top component for engaging with both the front and rear rocker stops. The top component and rocker stops are formed such that when a user is walking, the rocker travels from a forward position to a rear position, and when the rocker is in a forward position, the top component engages with the rear rocker stop, and when the rocker is in a rear position, the top component engages with the front rocker stop.

In another aspect, the sliding rod further comprises an alignment rod and a load rod. The alignment rod has a top portion, a bottom portion, and a length with an axis therethrough. The top portion of the alignment rod is pivotally attached with the body member. The load rod is in a fixed parallel alignment with the axis of the alignment rod. The load rod has a top part and a bottom part, where the load rod is connected with the alignment rod such that a length of the sliding rod is adjustable by sliding the top part of the load rod between the bottom portion and top portion of the alignment rod. Furthermore, the load pin is attached with the load road, whereby as a user walks and shifts from a swing phase to a stance phase, the load is transferred from the body member to the rocker. The shift causes the load pin to travel between the travel channel and the load channel, thereby shifting the load from the rocker onto the load pin and thereafter through the load rod and the foot analog to the ground surface.

In yet another aspect, the body member is rigid, allowing the passive exoskeleton to transfer weight from the body member and through the passive exoskeleton to the ground surface.

Additionally, the load rod further comprises an ankle joint attached with the bottom part of the load rod, where the ankle joint pivotally connects the load rod with the foot analog.

In another aspect, the rocker has a first side and a second side, and both the travel channel and the load channel are formed through the rocker from the first side to the second side.

Additionally, the present invention further comprises a foot connector attached with the foot analog, whereby a user may utilize the foot connector to securely attach the foot analog with the user's foot or shoe, thereby allowing the foot analog to maintain a position proximate the user's foot.

In yet another aspect, the present invention further comprises a body attachment attached with the body member. The body attachment is selected from a group consisting of a flexible harness, a belt, and suspenders. The body attachment is for attaching with a torso portion of a user, allowing the user to operate the exoskeleton and maintain the exoskeleton in a position proximate the user.

Additionally, the present invention further comprises a load frame attached with the body member, whereby a user may attach a load with the load frame and thereby transfer weight from the load, through the exoskeleton and to the ground surface.

Finally, it can be appreciated by one in the art that the present invention also comprises a kit and method for forming and supporting a load using the apparatus described herein.

DETAILED DESCRIPTION

The present invention relates to a load bearing apparatus, and more particularly to a passive exoskeleton that permits a load to be placed on the passive exoskeleton for at least a portion of the weight of the load to be transferred directly from the passive exoskeleton to a ground surface, causing the passive exoskeleton to support at least a portion of the load.

The following description, taken in conjunction with the referenced drawings, is presented to enable one of ordinary skill in the art to make and use the invention. Various modifications will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to a wide range of aspects. Thus, the present invention is not intended to be limited to the aspects presented, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. Furthermore, it should be noted that unless explicitly stated otherwise, the figures included herein are illustrated qualitatively and without any specific scale, and are intended to generally present the concept of the present invention.

In order to provide a clear frame of reference, first a glossary of terms used in the description and claims is given as a central resource for the reader. Next, a description of gait kinematics is provided to give an understanding of motion as applicable to the present invention. Third, a detailed description is provided to give specific details of the present invention. Finally, a description of the present invention during various motions is provided to further illustrate the utility of the present invention.

Before describing the specific details of the present invention, a central location is provided in which various terms used herein and in the claims are defined. The glossary provided is intended to provide the reader with a general understanding for the intended meaning of the terms, but is not intended to convey the entire scope of each term. Rather, the glossary is intended to supplement the rest of the specification in more clearly explaining the terms used.

Bias Block—The term “bias block” refers to a mechanism or device attached with a body member for engaging with a top component of a rocker, such that as a user walks backwards and shifts between the swing phase and stance phase, the top component of the rocker passes a point of equilibrium, with the bias block turning the rocker to aid the load pin in transferring between a load channel and a travel channel. The bias block is overridden when normal (i.e., forward) locomotion occurs.

Exoskeleton—The term “exoskeleton” refers to a load bearing apparatus for attaching with a user.

Foot-Analog—The term “foot-analog” refers to a structure or device that is similar to a human foot in that it is engageable with a ground surface and may used for transferring weight to the ground surface.

Gait Kinematics—The term “gait kinematics” refers to body mechanics associated with walking or stepping.

The present invention relates to a load-bearing passive exoskeleton. In order to better understand the invention, some introductory remarks are provided to help explain gait kinematics. As shown inFIG. 1, the gait cycle100can be divided into two phases: a stance phase102and a swing phase104. As shown inFIG. 1, the stance phase102accounts for approximately sixty percent (60%) of the gait cycle100during walking. It starts at heel-strike (initial contact)106and ends at toe-off (pre-swing)108. The swing phase104accounts for approximately 40% of the gait cycle100and is when the limb is not loaded. So, for example, when one limb is in a loading response110, the other limb is in a pre-swing108.

In order for the passive exoskeleton to function properly, two fundamental criteria should be met: (1) a rod (brace) should support a load during the stance phase102, but not inhibit motion during the swing phase104, and (2) the rod (brace) must allow a normal range of motion, while comfortably supporting a load.

There are a number of ways that such a structure could support a load. One possibility is to have a rigid rod that maintains a fixed distance between a hip114and an ankle116. Since a user's knee118would be locked in this case (i.e., it doesn't bend), the user would be forced to walk unnaturally, with unbending knees. Although the rod could hold part of the weight of the load, such a device would be uncomfortable because of this “unbent knee” problem.

Another possibility would be to have two rods connected by a hinge joint at the knee118. A problem with this, however, is that a hinge cannot support weight by itself. In this case, a user would need to use leg muscles acting at the knee118to prevent falling. Similarly, a hinged brace would require a muscle or actuator to mimic the function of the knee118. Such a system, however, is not practical using current actuator technologies. Instead of adding complexity and requiring self-contained power to drive these actuators, the present invention pursues a different strategy, to create a simple device that requires no electrical power.

One possible passive solution would be to use a spring at the hinged knee joint. The spring could take up part of the load and act as the constant muscle for the knee joint. Adding a spring would allow some bending of the knee118and better gait kinematics. A problem with this approach, however, is that the system should carry the load during the stance phase102, but not resist the leg force during the swing phase104(when the leg is swinging forward and is not supporting the weight). Otherwise, the benefit in having the device support the load during the stance phase102of the stride would be negated during the swing phase104of the stride. In this example, any time the knee118is bent, force must be exerted to compress the spring. After heel-strike106, during the stance phase102of the gait cycle100, a spring would be desirable because the weight of the load is used to compress the spring. However, after toe-off and during the swing phase104, the spring is undesirable because the user must use considerable force to bend the knee118and bring up the heel119to allow the toe120to clear the ground during the swing phase104. During the swing phase104, the user would be “fighting the spring.”

Another possible solution is to have one rigid rod between the hip114and ankle116, but to allow the user's knee118to bend. The difficulty with this solution is that when the user's knee118bends, the distance between the hip114and ankle116varies. With a single rod, this would result in the rod protruding above the user's hip114when the knee118is bent. In this configuration, the load may be attached with the end of the rod to allow its weight to be transferred to the rod. Therefore, the load would bounce up and down during walking. Furthermore, this system would still require the user to lift the entire weight of the load when bring up their heel, similar to the “fighting the spring” problem previously described.

The solution proposed by the present invention decouples the stance102and swing104phases of walking. This allows the exoskeleton to bear a load during the stance phase102, but to bear substantially no load during the swing phase104(recovery), so the individual does not fight the device when swinging a leg forward. This can be accomplished through use of the exoskeleton described herein. Since the distance between the hip114and ankle116is also allowed to vary, the knee118can be bent and the user does not have the “unbent knee” problem. On the other hand, the rod bears no load during the swing phase104(recovery) so there is no “fighting the spring” problem. In addition, a mechanism at the ankle116allows the weight of the load to be transferred to a ground surface and eliminates the need for the user to exert extra effort to lift their ankle116during the swing phase104. The details of the exoskeleton described herein are further described below.

FIG. 2illustrates a passive exoskeleton200according to the present invention. The exoskeleton200comprises a body member202for transferring weight of a load204to a sliding rod205, and thereafter to a ground surface206. Additionally, a load frame207may be attached with the body member202, thereby allowing the load204to be secured with the exoskeleton200. The body member202may be any suitable mechanism for transferring and bearing weight, non-limiting examples of which include a rigid plate and a rigid hip attachment. For example, the rigid hip attachment may be a metallic bar that wraps around a user's hip. In this aspect, the weight of the load204would be transferred to the metallic bar, and thereafter through the connected sliding rod205and on to the ground surface206.

Additionally, a body attachment208may be attached with the body member202. The body attachment208is for attaching the exoskeleton200with a torso portion of a user, allowing the user to operate the exoskeleton200and maintain the exoskeleton200in a position proximate the user. The body attachment208may be any suitable mechanism or device for maintaining one object proximate another, non-limiting examples of which include a flexible harness, a belt, and suspenders.

The sliding rod205is attached with the body member202. The sliding rod205is constructed of any suitably rigid material, a non-limiting example of which includes metal, plastic, and composite materials. The sliding rod205comprisesan alignment rod212and a load rod214. The alignment rod212has a top portion216, a bottom portion218, and a length with an axis220therethrough. The alignment rod212may be any suitable mechanism or device for maintaining an alignment of an object, non-limiting examples of which include a cylindrical tube, an elongated plate, a rod, and a metallic bar. The top portion216of the alignment rod212is attached with the body member202through a mechanism that allows movement therebetween, a non-limiting example of which includes being pivotally attached through use of a pin, or ball joint such as a hip joint.

The load rod214is in a fixed parallel alignment with the axis220of the alignment rod212. The load rod214is a mechanism or device for bearing a load, non-limiting examples of which include a cylindrical tube, an elongated plate, a rod, and a metallic bar. The load rod214has a top part222and a bottom part224, and is connected with the alignment rod212such that a length of the sliding rod205is adjustable by sliding the top part222of the load rod214between the bottom portion218and top portion216of the alignment rod212. As a non-limiting example, the alignment rod212is a cylindrical tube and is positioned within a larger cylindrical tube of the load rod214, allowing the two rods to be slid past each other, thereby varying the length of the sliding rod205.

In order to transmit the weight of the load204to the ground, the load rod214must be connected to something in contact with the ground. This is accomplished through use of a ground surface engage-able foot analog226that is attached with the bottom part224of the load rod214. The foot analog226is attached with the load rod214through a suitable mechanism or device allowing movement therebetween, a non-limiting example of which includes being pivotally attached through use of an ankle joint228. The foot analog226is constructed such that it is engageable with both a ground surface and with a user's foot. As a non-limiting example, the foot analog226may be a platform for connecting with a bottom side of a user's shoe.

If the load rod214was only attached to the user's boot at the ankle with no foot analog226, during toe-off the user would need to use a calf muscle to lift up the heel and thus the entire weight of the load204. Having to lift the entire weight of the load204at each toe-off would be difficult to do and could present a significant mechanical burden. By using a foot analog226such as a platform, the load rod214is able to support the weight of the load204and transmit it to the ground without requiring additional effort from the user's calf muscle.

A foot connector230is attached with the foot analog226, allowing a user to securely attach the foot analog226with the user's foot or shoe, thereby allowing the foot analog226to maintain a position proximate the user's foot. The foot connector230may be any suitable mechanism or device for fastening one object against another, non-limiting examples of which include Velcro™ straps, clips, and buckles.

A user's leg can only support a load during the stance phase. For example, a user has two legs and as the user walks, each leg shifts between the stance and swing phases. While one leg is substantially in the swing phase, the other leg is substantially in the stance phase. Accordingly, during the swing phase, the other leg is supporting the load as it is in the stance phase. Therefore, the exoskeleton further comprises a rocker300, as shown inFIG. 3. The rocker300helps support the weight of a load during the stance phase, but does not inhibit motion during the swing phase. The rocker300is attached with the body member202through a mechanism or device allowing movement therebetween, a non-limiting example of which includes being pivotally attached through use of a hip pin or a ball joint. The rocker300has a travel channel302and a load channel304incorporated therein. Furthermore, both the travel channel302and the load channel304pass through the rocker300from a first side306to a second side308.

The travel channel302is an elongated channel constructed such that it is oriented directionally from proximate the body member202to the ground surface206. The load channel304is an elongated channel positioned such that an angle312between the load channel304and the travel channel302is less than ninety degrees.

A load pin314is attached with the top part222of the load rod214. The load pin314is positioned such that it is operably attached with the rocker300through both the travel channel302and the load channel304. When the load pin314is in the travel channel302, the two rods can slide relative to one another and substantially no weight is carried by that particular rocker300.

When a user walks and shifts from a swing phase to a stance phase, the shift causes the load pin314to travel down315the travel channel302and into the load channel304, thereby shifting the load from the rocker300, onto the load pin314, and thereafter through the load rod214and the foot analog to the ground surface206.

The body member202has a front side316and a rear side318. A front rocker stop320is attached with the front side316of the body member202and a rear rocker stop322is attached with the rear side318of the body member202. When a user is walking, the rocker300swings between a forward position324and a rear position326. When the rocker is in a forward position324, a top component328of the rocker300engages with the rear rocker stop322. When the rocker300is in a rear position326, the top component328engages with the front rocker stop320.

A bias block330is attached with the body member202to divide the region between the two rocker stops320/322. Without the bias block330, the rocker300has no interaction at its top component328until it hits the rocker stops320/322at the limit of its travel in a full stride gait. To aid the bias block330in interacting with the top component328, a pressure mechanism332is attached with the bias block330. The pressure mechanism332is attached with the bias block in a suitable manner to force the bias block330against the top component328of the rocker300. As a non-limiting example, the pressure mechanism332is placed between the body member202and the bias block330, and is a mechanism with suitable expansion and contraction properties. As non-limiting examples of suitable mechanisms, the pressure mechanism332may be a spring or hydraulic system forcing the bias block330against the top component328. For example, if a hydraulic system, a hydraulic mechanism (e.g., such as a shock similar to those used in automobiles) may be attached with the bias block330to force it against the top component328, such that as the top component328moves, the hydraulic system adjusts itself to continually force the bias block330into the top component328.

The bias block330serves to rotate the rocker300such that the load pin314is moved from the load channel304to the travel channel302, or back. The pressure applied by the bias block330against the top component328of the rocker300(i.e, via the pressure mechanism332) is sufficient to rotate the rocker300either clockwise or counter clockwise when the stride/gait shifts the load off the load pin314. When under load, the load pin314will be locked in the load channel304and the bias block330will not be able to rotate the rocker300.

The bias block330rotates the rocker300in the same direction as the top is inclined (with respect to the quasi-equilibrium point). This means when walking backwards, the top of the rocker is inclined clockwise as the user steps backward. As the load pin314reaches the intersection of the load304and travel channels302, the bias block330further rotates the rocker300clockwise which moves the load pin314from the travel channel302into the load channel304. This works in the same way as the user (still walking backwards) goes into the recovery part of the stride and lifts up thier foot (having shifted the weight off that leg onto the other), with the bias block330rotating the rocker300counterclockwise to move the load pin314from the load channel304into the travel channel302, permitting the user to lift their foot without opposition of the passive exoskeleton200.

Further, the bias block330can be angled to permit vertical engagement when taking stairs either upward or downward. Ascent techniques depend on proper bias block330angle and a proper travel channel302length (i.e., minimum length must exceed the height of a stair step). However, the stair ascent is a matter of technique. The important part is the bias block330which permits the rocker300to engage and disengage during the gait. Details of the stair ascent or descent are dependent on the particular configuration (i.e., orientation) of the bias block330.

For example, the bias block330assumes a smaller step backward than forward, where the rocker stops must be set far enough apart to provide the bias block330with sufficient space to function. The bias block330function is dependent on the orientation of the load channel304to the travel channel302. Thus, if the rocker300were flipped, and the load channel304were to head in the opposite direction, then small steps forward would be enabled by the bias block330and large steps backward by the rocker stops.

To neutralize (i.e., turn off) the passive exoskeleton, a neutral block334is attached with the top portion216of the alignment rod212. The neutral block334is configured such that it is engage-able with the top component328of the rocker300. When the load pin is in the travel channel, the rocker is aligned with the sliding rods205and, more particularly, with the alignment rod212. An engaging portion336(a non-limiting example of which includes a slot) exists in the top component328of the rocker300, such that when the engaging portion336is engaged between the alignment rod212and the top component328(i.e., when directly aligned), the rocker300will remain aligned with the sliding rod205. This alignment keeps the load pin314affixed in the travel channel302.

When the neutral block is engaged334and the load pin314is affixed in the travel channel302, the passive exoskeleton200does not bear any of the load and therefore does not benefit a user. This is because the load pin314remains in the travel channel302, the travel channel302remains aligned with the sliding rod205, and the load pin314does not enter the load channel304. Additionally, when the neutral block334is engaged, the rocker300is not free to rotate and therefore does not interfere with the stride of the user during the user's gait.

(4) The Present Invention in Motion

The passive exoskeleton of the present invention is well-suited for both forward and reverse motion. Although the rocker and rocker stops are sufficient for forward motion, the rocker and rocker stops alone do not allow for sufficient reverse motion. Accordingly, the present invention includes the bias block and pressure mechanism which aids in rotating the rocker during reverse motion. To improve clarity, this section is divided into two subsections, forward motion and reverse motion.FIGS. 4 through 30Billustrate forward motion, showing the function of the rocker and rocker stops.FIGS. 31A through 43Billustrate reverse motion, showing the function of the rocker, the bias block, and the pressure mechanism, as taken from a right hip view. Although the bias block is also functional during forward motion, it is illustrated herein to emphasize its applicability to reverse motion. As can be appreciated by one in the art, the described motions of the bias block (i.e., while in backward motion), can be reversed to illustrate the bias block in a forward motion.

(i) Forward Motion

As shown inFIG. 4, during heel-strike106(initial contact), the load pin314is in the load channel304. As weight is transferred to a user's right leg400, the weight of a load is transferred through the body member and rocker300, via the load pin314, to the load rod214and the ground206. The rocker300continues to bear weight of the load during the stance phase as the load pin314remains in the load channel304.

FIGS. 5,6, and7illustrate the loading response, mid-stance and terminal stance positions respectively. As shown inFIGS. 5,6, and7, during these positions the weight of the load continues to be borne by the load pin314, which transfers the weight from the rocker300to the load rod214.

As shown inFIG. 8, the weight of the load continues to be borne by the load pin314until the pre-swing phase, just before toe-off. At this point, the top component328of the rocker300reaches the front rocker stop320, which prevents further rotation of the rocker300. Before completing the stance phase, the load pin314continues to move up and to the left since the right knee118is bending. However, once the rocker300can no longer rotate, the load pin314is forced up into the travel channel302.

As shown inFIG. 9, during the initial swing and as the knee118bends, the distance between the ankle116and hip114joint decreases. The load pin314then travels along the travel channel302and substantially no weight is transferred from the rocker300to the load rod214.

The majority of variation in the hip-to-ankle distance900occurs during the swing phase. This is not a problem because the load pin314is in the travel channel302during this portion of the stride and the two rods (i.e., alignment rod212and load rod214) can slide freely relative to one another. As long as the stance and swing phases can be de-coupled using the rocker300, it is possible to use the rocker's300geometry in conjunction with a variety of springs and dashpots to smooth the motion. A spring placed in the load channel304, for example, would help smooth the motion of the load pin314during the stance phase. This would also prevent the load pin314from reaching the base of the load channel304and would therefore allow a smaller angle312between the load channel304and the travel channel302. This angle312could compensate for some variation in the hip-to-ankle distance900during the stance phase.

FIGS. 10 and 11illustrate the mid swing and terminal swing positions respectively. As shown inFIGS. 10 and 11, as the user continues to walk and the leg400swings forward1000, the rocker300rotates in a counter-clockwise direction1002, with the load pin314continuing to travel along the travel channel302. While traveling in the travel channel302, the load pin314carries no load until the point where the right leg400is about to touch the ground again.

As shown inFIG. 12, before the end of the swing phase, the top component328hits the rear rocker stop322. Any further motion of the leg forward1000causes the load pin314to move into and along the load channel304, allowing the rocker300to take up the weight of the load after heel-strike106.

FIGS. 13A through 20Bare perspective view illustrations of a passive exoskeleton200, both attached proximate a user (i.e.,FIGS. 13A,14A,15A,16A,17A,18A,19A, and20A) and without a user (i.e.,FIGS. 13B,14B,15B,16B,17B,18B,19B, and20B) as one side of the exoskeleton200travels through a stance phase102and thereafter a swing phase104.

FIGS. 21A through 25Bare side view illustrations of a passive exoskeleton200, both attached proximate a user (i.e.,FIGS. 21A,22A,23A,24A, and25A) and without a user (i.e.,FIGS. 21B,22B,23B,24B, and25B) as one side of the exoskeleton200travels through a stance phase102.

FIGS. 26A through 30Bare front view illustrations of a passive exoskeleton200, both attached proximate a user (i.e.,FIGS. 26A,27A,28A,29A, and30A) and without a user (i.e.,FIGS. 26B,27B,28B,29B, and30B) as one side of the exoskeleton200travels through a stance phase102.

(ii) Reverse Motion

FIGS. 31A through 43Bare side and top view illustrations of the rocker300and bias block330motion while a user is walking backwards3104(i.e., reverse motion). As shown inFIGS. 31A through 43B, the bias block330is added to divide the region between the two rocker stop320/322into five zones. The two rocker stops320/322represent two zones, allowing for give/compression. A quasi-equilibrium point3100represents a zone of division between the two divided zones3102. The two divided zones3102represent the area between the rocker stops320/322and the quasi-equilibrium point3100. The bias block330is curved, and aligned radially with the main pin (i.e., hip pin) so that the quasi-equilibrium point3100is aligned such that when loaded, the user's posture at rest when both feet are close together (i.e., standing) positions the rocker300and the bias block330in the quasi-equilibrium position3100.

Also, the bias block330functions in the two divided zones3102between the rocker stops320/322. A user wearing the exoskeleton can walk backwards3104when the bias block330is engaged, provided the user takes a smaller stride backwards3104than the rocker stops320/322are set for forward3106motion.

Also, as noted inFIGS. 31A through 43B, the spring force of the pressure mechanism332is represented by an arrow3108. Although not to scale, the size of the arrow3108is proportional to the amount of force on the bias block330.

FIGS. 31A and 31Bare side and top view illustrations of the rocker300and bias block330in a default quasi-equilibrium position. As shown, the load pin314is in the travel channel302. The quasi-equilibrium position generally occurs during the recovery phase, when the foot is off of the ground.FIG. 31Ais a side view of the rocker300, whileFIG. 31Bis a top view of the rocker300and bias block330.

FIGS. 32A and 32Bare side and top view illustrations of the rocker300and the bias block330as a user begins a backward step during the recovery phase (i.e., with the foot off of the ground). As shown, the load pin314is still in the travel channel302as the bias block330begins exerting pressure against the top component328of the rocker330, thereby forcing the top component328toward the front rocker stop320.FIG. 32Ais a side view of the rocker300, whileFIG. 32Bis a top view of the rocker300and bias block330.

FIGS. 33A and 33Bare side and top view illustrations of the rocker300and the bias block330during a backward step extension of the recovery phase (i.e., with the foot still off of the ground). As shown, the load pin314is still in the travel channel302as the bias block330continues exerting pressure against the top component328of the rocker330, thereby forcing the top component328toward the front rocker stop320.FIG. 33Ais a side view of the rocker300, whileFIG. 33Bis a top view of the rocker300and bias block330.

FIGS. 34A and 34Bare side and top view illustrations of the rocker300and the bias block330during a backward step as the foot has just touched the ground (i.e., transition to stance phase). As shown, the load pin314is at the intersection of the travel channel302and the load channel304, with the bias block330continuing to exert pressure against the top component328of the rocker330, thereby forcing the top component328toward the front rocker stop320and the load pin314into the load channel304.FIG. 34Ais a side view of the rocker300, whileFIG. 34Bis a top view of the rocker300and bias block330.

FIGS. 35A and 35Bare side and top view illustrations of the rocker300and the bias block330during a stance phase of the backward step with the foot on the ground. As shown, the load pin314is in the load channel304.FIG. 35Ais a side view of the rocker300, whileFIG. 35Bis a top view of the rocker300and bias block330.

FIGS. 36A and 36Bare side and top view illustrations of the rocker300and the bias block330during a furtherance of the backward step stance phase with the foot still on the ground. As shown, the load pin314is still in the load channel304.FIG. 36Ais a side view of the rocker300, whileFIG. 36Bis a top view of the rocker300and bias block330.

FIGS. 37A and 37Bare side and top view illustrations of the rocker300and the bias block330during a furtherance of the backward step stance phase with the foot still on the ground. As shown, the load pin314is still in the load channel304.FIG. 37Ais a side view of the rocker300, whileFIG. 37Bis a top view of the rocker300and bias block330.

FIGS. 38A and 38Bare side and top view illustrations of the rocker300and the bias block330during a furtherance of the backward step stance phase with the foot still on the ground. As shown, the load pin314is still in the load channel304.FIG. 38Ais a side view of the rocker300, whileFIG. 38Bis a top view of the rocker300and bias block330.

FIGS. 39A and 39Bare side and top view illustrations of the rocker300and the bias block330during a furtherance of the backward step stance phase with the foot still on the ground. As shown, the load pin314is still in the load channel304, while the top component328of the rocker300passes the quasi-equilibrium point.FIG. 39Ais a side view of the rocker300, whileFIG. 39Bis a top view of the rocker300and bias block330.

FIGS. 40A and 40Bare side and top view illustrations of the rocker300and the bias block330during a backward step as the foot still touches the ground but is no longer loaded (i.e., transition to swing phase). As shown, the load pin314is at the intersection of the travel channel302and the load channel304, with the bias block330exerting pressure against the top component328of the rocker330, thereby forcing the top component328toward the rear rocker stop322and the load pin314toward the intersection of the load channel304and travel channel302.FIG. 40Ais a side view of the rocker300, whileFIG. 40Bis a top view of the rocker300and bias block330.

FIGS. 41A and 41Bare side and top view illustrations of the rocker300and the bias block330during a furtherance of the backward step swing phase with the foot no longer touching the ground (i.e., in the air). As shown, the load pin314has shifted into the travel channel302, while the top component328of the rocker300begins returning toward the quasi-equilibrium point.FIG. 41Ais a side view of the rocker300, whileFIG. 41Bis a top view of the rocker300and bias block330.

FIGS. 42A and 42Bare side and top view illustrations of the rocker300and the bias block330during a furtherance of the backward step swing phase with the foot still in the air. As shown, the load pin314is in the travel channel302, while the top component328of the rocker300continues returning mid-stance the quasi-equilibrium point.FIG. 42Ais a side view of the rocker300, whileFIG. 42Bis a top view of the rocker300and bias block330.

FIGS. 43A and 43Bare side and top view illustrations of the rocker300and bias block330after having returned to the default quasi-equilibrium position during the recovery phase, with the foot still off of the ground. As shown, the load pin314is still in the travel channel302.FIG. 43Ais a side view of the rocker300, whileFIG. 43Bis a top view of the rocker300and bias block330.

As mentioned previously, motion of the bias block was illustrated herein during backward motion. However, and as can be appreciated by on in the art, the motion of the bias block is not limited to backward motion and operates in a similar fashion while a user is traveling forward.