Disclosed embodiments are related to devices for assisting motion of a joint.
Both rigid and soft robotic exosuits have been used for assisting human motion in both healthy and ailing populations. For example, previous soft exosuits focusing on the lower limb(s) of a user have used Bowden cable actuators which allow the user to carry the majority of the system mass at the torso while providing assistive forces distally at the hip, knee and/or ankle.
In one embodiment, a device for assisting motion of a joint includes a motor, a mandrel operatively coupled to the motor, a tether operatively coupled to the mandrel and configured to wind onto the mandrel when the mandrel is rotated by the motor, a guide configured to guide the tether as it is wound onto the mandrel, and at least one spring. The guide is configured to move in a direction substantially parallel to an axial length of the mandrel. The at least one spring is configured to bias the guide to a neutral position along the length of the mandrel.
In another embodiment, an actuator includes a tether and a tether enclosure configured to at least partially enclose at least a portion of the tether, where the tether enclosure is configured to extend and/or retract when the tether extends and/or retracts from the actuator.
In yet another embodiment, a device for assisting motion of a joint includes a first anchor configured to be attached to a first body portion on a first side of the joint, a second anchor configured to be attached to a second body portion on a second side of the joint, an actuator operatively coupled to the first anchor and the second anchor, and a support operatively coupled to the first anchor and the second anchor. The support is also configured to substantially maintain a position of the first anchor relative to the first body portion and/or a position of the second anchor relative to the second body portion. The support is configured to apply a torque to the joint when motion of the joint deforms the support.
In still another embodiment, a device for assisting motion of a joint includes a first anchor configured to be attached to a first body portion on a first side of the joint, a second anchor configured to be attached to a second body portion on a second side of the joint, a spring operatively coupled to the first anchor and the second anchor, and an actuator operatively coupled to the first anchor and the second anchor. Actuating the actuator applies a torque about the joint that is resisted by a reaction torque from the spring.
In another embodiment, a method of assisting motion of a joint includes applying a first torque to the joint in a first direction with an actuator, and applying a second torque to the joint in a second direction with a spring that is antagonistic to the first torque.
It should be appreciated that the foregoing concepts, and additional concepts discussed below, may be arranged in any suitable combination, as the present disclosure is not limited in this respect. Further, other advantages and novel features of the present disclosure will become apparent from the following detailed description of various non-limiting embodiments when considered in conjunction with the accompanying figures.
In cases where the present specification and a document incorporated by reference include conflicting and/or inconsistent disclosure, the present specification shall control. If two or more documents incorporated by reference include conflicting and/or inconsistent disclosure with respect to each other, then the document having the later effective date shall control.
The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:
As described above, previous soft exosuits have used Bowden cables to control actuation of the user's joints. However, Bowden cables often use stiff steel rope, which may be heavy, may require powerful motors to manipulate, and/or may have a low bend radius. While such an actuation strategy may be appropriate in certain applications, heavy tethers and large actuators may be undesirable in other applications, such as with users who may be impaired or otherwise unable to carry heavy components.
The Inventors have appreciated that a single unidirectional actuator may be combined with a spring to assist motion of a joint in two directions. For example, an actuator may exert a torque on a joint in one direction, while a spring may exert an antagonistic torque that opposes the torque applied by the actuator. Whereas before two actuators may have been used in an exosuit to achieve two degrees of freedom, the combination of an actuator and an antagonistic spring may allow a single actuator to achieve similar functionality, potentially yielding a smaller, lighter, less expensive, and less complex system. Such an arrangement may be particularly advantageous in certain populations of users. For example, stroke patients may benefit from a light system that applies a constant toe-up assistance to an ankle joint. However, systems used for assisting the motion of other joints are also contemplated as described further below.
In some embodiments, a device for assisting motion of a joint may be configured to provide assistance to a user's ankle. The device may comprise an actuator combined with a spring. Throughout the gait cycle, the spring may provide a dorsiflexion (toe up) torque to the ankle. When push-off assistance is needed, the actuator, located on the user's calf, may be activated to exert a plantarflexion (toe down) torque that overcomes the torque of the spring and delivers a net plantarflexion torque to the ankle. When push-off assistance is no longer needed, the actuator may be deactivated, enabling the dorsiflexion torque from the spring to provide a net dorsiflexion torque to the ankle. Such a configuration may yield a favorable failure mode, such that if the actuator fails, the user's ankle will default into a dorsiflexed state. However, in other embodiments, the torques provided by the spring and the actuator may be reversed, such that the spring provides a plantarflexion torque and the actuator applies a dorsiflexion torque. Additionally, depending on the particular mode of operation, the actuator torque applied to a joint may be controlled relative to the torque applied to the joint by an associated spring to apply a desired net torque at any point within a movement cycle of the joint as elaborated on further below.
It should be understood that the springs discussed herein relative to the various disclosed embodiments may correspond to any appropriate type of spring or compliant structure capable of applying the desired torque and/or force in a desired direction to an associated joint. For example, appropriate types of springs may include, but are not limited to, one or more selected from the group of: a tension spring, a compression spring, a torsional spring, a leaf spring, a compliant elongated structure such as a tube, rod, shaft, or other appropriate structure which may including one or more curves along its length, and/or any other compliant structure that is configured to provide the desired operating properties to apply a torque to a joint. In some embodiments, a spring may have a rotational stiffness about a joint between about 0.15 Nm/° and 0.6 Nm/°. For example, a spring may have a rotational stiffness of 0.3 Nm/°. Of course, it should be understood that a spring may have any appropriate range of rotational stiffness including ranges both less than and greater than those noted above as the disclosure is not limited in this fashion.
The actuators described herein may include any appropriate type of motor. For example, an actuator may include a brushed DC motor, a brushless DC motor, a stepper motor, and/or any other appropriate type of motor. In some embodiments, an actuator may be a linear actuator, such as a solenoid, a McKibben actuator, or a leadscrew. In some embodiments, an actuator may be directly connected to both anchors, a tether may extend from the actuator to one anchor, the actuator may be connected to anchors located on opposing sides of a joint via two or more separate tethers, and/or any other appropriate arrangement for connecting the actuator to the associated portions of a device may be used. In some embodiments, an actuator may be removable from an assistive device. If the device includes a spring, removing the actuator may yield a passive system that may provide joint assistance in only a single direction using the spring. Additional discussion of actuators, associated springs, and overall devices is provided in further detail below.
For the sake of clarity a majority of the embodiments described herein are directed to a device used to apply an assistive torque to an ankle joint. However, should be understood that the systems and methods described herein are not limited to use only with ankle joints. For example, the actuators, devices, and methods described herein are generally applicable for applying assistive torques to any joint about which it is desirable to apply an assistive torque during a motion cycle, which includes, for example, a gait cycle. This may include, but is not limited to, joints such as a knee, hip, ankle, wrist, elbow, shoulder, back, or any other suitable joint. Accordingly, it should also be understood that the anchors of a device may be attached to any appropriate portion of a person body including, but not limited to, a foot, calf, thigh, waist, torso, shoulder, back, upper arm, forearm, hand, neck, head, and/or any other appropriate portion.
In addition to the various portions of a body a device may be used to apply assistive torques to, a device may include any appropriate type of anchors for maintaining a position and/or orientation of a portion of a device relative to an underlying portion of a user's body. For example, an anchor may include cuffs, straps, flexible garments such as compression sleeves, inextensible garments, semi-rigid shells and/or rigid shells contoured to an underlying body portion of a user, and/or any other appropriate structure capable of positioning and maintaining a portion of a device on a desired portion of a user's body. For example, an anchor on the upper calf of a user may be made of a substantially inextensible garment material shaped to conform to the contours of the user's calf when worn.
In some applications, device comfort during operation may impact the duration for which a user may be willing to use the device. For example, in a soft exosuit, the portions of the device positioned on the underlying tissue may be supported entirely by shear forces on the human body. This loading may lead to discomfort and may result in the wearable component's position on a user's body drifting during use where the underlying body anatomy is not shaped appropriately to oppose this motion. Thus, when larger assistive forces are used, increased drifting of the system components may occur. Accordingly, a fully soft architecture may not be ideal for prolonged wear in some applications. Rather, a device may include one or more supports that may be employed to reduce the shear loading applied to the underlying portions of a user's body. For example, one or more supports may be attached to and extend between two anchors of a device positioned on either side of a joint. The one or more supports apply a force to the two anchors that acts to substantially maintain the two anchors in a spaced apart configuration. In other words, the support may apply a forces to each anchor that includes a component directed away from the other anchor which may help to hold the anchors in place and offset at least a portion of the shear load applied to the underlying portions of a user's body. It should be understood that while the relative position and/or orientation of the anchors may be substantially maintained relative to one another some minor shifting between the anchors may occur but the overall general position and/or orientation may be maintained. Depending on the particular embodiment, and as elaborated on further below, the one or more supports may either be one or more rigid supports and/or one or more compliant supports that are capable of deforming during use may be used. For example, a rigid support may include one or more rotatably coupled segments connected using any appropriate coupling such as a hinge, pin joint, or similar arrangement. Alternatively, a compliant structure that is capable of deforming during movement of a joint while providing a desired axial stiffness and/or rotational stiffness may be used. Specific examples of these structures are provided in more detail below.
In view of the above, in some embodiments, a device includes a first anchor configured to be attached to a first body portion on a first side of the joint and a second anchor configured to be attached to a second body portion on a second side of the joint. An actuator is operatively coupled to the first anchor and the second anchor. A support is operatively coupled to the first anchor and the second anchor. In some embodiments, the support is compliant such that it may be viewed as a spring. Alternatively, the device may include a spring that is separate and apart from the support. In those embodiments in which the support is a spring, the spring comprises one or more selected from the group of a tension spring, a torsional spring, a leaf spring, and a curved elongated structure. In some embodiments, the support is substantially aligned with and/or extends in a direction substantially parallel with an axial direction of a limb segment associated with the support in at least a portion of a motion cycle. In either case, during operation, the support may help maintain a spacing and/or orientation of the first anchor and the second anchor relative to each other and/or the underlying portion of a body part associated with each anchor during mode of operation.
In some embodiments, two or more supports may be disposed on opposing sides of a user's joint such that the supports do not impede motion of the joint. For example, in an actuation module that is configured to assist a user's ankle, two supports may be included: one on the lateral side of the ankle, and one on the medial side of the ankle. The two supports may be interchangeable, or each support may be specifically designed for a single side of a joint. In some embodiments, a support may be configured to have a multi-dimensional shape, and may wrap around the front or back of a user's limb segment and/or joint. Accordingly, it should be understood that a support for a joint may have a number of different configurations and may be positioned on any number of different sides of a joint depending on the particular design.
In one embodiment, a support may be a curved elongated structure made from a compliant material. Such an embodiment may provide a wide range of motion and may not need precise alignment with an axis of rotation of a joint as may be needed with rigid structures or certain types of springs. When loaded by an actuator, the geometry and material properties of the curved elongated structures may yield low stiffness when considering rotation of a user's foot/other joint, but may yield relatively high stiffness when considering vertical translation of an anchor at the user's calf, which may result in a significant reduction in shear loading at the user's body.
In some embodiments of a curved elongated structure, the elongated structure may have a cross section with a diameter, or other transverse dimension, between about 0.25 inches and 0.5 inches including, for example 0.375 inches. The elongated structure may also include a curve along at least a majority of its length, and in some instances along substantially its entire length. The curve may have a radius of curvature between about 20 cm and 40 cm, though instances in which multiple curves with similar or different radii of curvature are used are also possible. The length of the compliant support, which may also be viewed as a spring, may be any length suitable for the body dimensions of a given user. However, in embodiments in which the support is used for applying a torque about an ankle of a user, the support may have a distance between its two opposing ends that is between or equal to 32 cm and 53 cm, depending on the body dimensions of a user. However, it should be understood that the stiffness and other properties of a support are dependent on both the material properties and overall geometry of the support. Accordingly, depending on the material used, it should be understood that different dimensions both greater and less than those noted above may be used as long as the support provides a desired rotational and compressive stiffness.
As noted above, in some embodiments, a support may apply forces to maintain the anchors of a device in a desired position and/or orientation relative to each other when worn by a user. Accordingly, an appropriate stiffness for providing this force may be selected. In some embodiments, a support may have a linear stiffness of at least 6 N/mm, 8 N/mm, 10 N/mm, or any other appropriate stiffness. Correspondingly, a support may have a linear stiffness less than about 15 N/mm, 10 N/mm, and/or any other appropriate stiffness. Combinations of the foregoing are contemplated including for example a support with a linear stiffness between or equal to 6 N/mm and 15 N/mm or 8 N/mm and 10 N/mm. Of course depending on a particular application linear stiffnesses both greater and less than those noted above are contemplated.
A support, including a compliant support, may be made from any appropriate material with a desired combination of elasticity and yield strength for a given application. For example, in one embodiment a support may be made from a polyether ether ketone (PEEK) though any appropriate plastics, metal, composite material (e.g. polymer fiber composites and other composites), and/or any other appropriate material may be used to form a support as the disclosure is not limited in this manner.
In some embodiments, a compliant support that is configured to act as a spring to apply a torque around an associated joint may be configured such that it deforms along an expected path of motion of an associated body part during joint articulation. For example, the compliant support may include one or more curves as noted above. However, the one or more curves may be selected such that as the compliant support is deformed during use to apply a torque to the associated joint an end of the compliant support follows a natural path of motion of the body portion it is attached to around the joint. In one such embodiment, a top portion of a compliant support may be held stationary at a position on a user's calf and a bottom portion of the compliant support may be attached to a shoe, insole, supporting plate, or other structure attached to a foot of a user such that the bottom portion of the compliant support attached to the foot follows the path of motion of the foot as it is deformed and applies a desired torque to the ankle joint. Of course it should be understood that similar functionality may be applied for any number of other joints as the disclosure is not limited to only ankle joints.
In some embodiments, a joint-agnostic actuator of a device for assisting motion of a joint may include a motor, a mandrel, and a tether. The motor may be operatively coupled with the mandrel in any appropriate manner to selectively rotate the mandrel in either one or both directions. Depending on the particular embodiment, the motor may be coupled to the mandrel either by a direct connection, a low gear ratio transmission, and/or any other appropriate transmission as the disclosure is not limited in this fashion. When rotated in a first direction, the mandrel's rotation may cause the tether to spool along the mandrel. In some instances, it may be advantageous for the tether to wind in a single layer around the mandrel to avoid inconsistencies in force associated with changes in radius from the tether being wound in multiple layers and/or to reduce wear on the tether during use. Thus, in some embodiments, an actuator may include a guide that is configured to guide the tether as it winds around the mandrel to ensure the tether is wound in a single layer on the mandrel as detailed further below.
In some embodiments, an actuation module may include an actuator and associated tether enclosure. The tether enclosure may be an elastic material, such as an elastic textile, or other material that surrounds at least a portion of the tether extending away from a portion of the actuator the tether enclosure is attached to. Thus, depending on the particular construction, the tether enclosure of the actuation module may protect a user from abrasion and tangling with the tether, may protect the inside of the actuator from environmental contaminants, and/or may allow the tether to be coated with a wet lubricant due to the enclosure helping to isolate the tether from the user which can significantly improve tether lifetime.
As used herein a tether may refer to any flexible elongated structure capable of being spooled into and out of an actuator for applying a tension force to a desired portion of the devices described herein. For examples, a tether may include wire ropes as may be seen in Bowden cables, braided synthetic or natural ropes, flexible flat straps, and/or any other appropriate flexible structure. Accordingly, the above noted and other appropriate types of tethers may be used with any of the embodiments described herein. However, in some embodiments, such as embodiments where smaller sized mandrels are used, a more flexible tether as compared to the relatively stiff wire ropes used in Bowden cables may be used. For instance, a flexible braided rope, or other similarly flexible tether, may be used because they are capable of accommodating a tighter bend radius without experiencing accelerated fatigue and failure in addition to the reduced motor torques associated with spooling a relative flexible tether onto a smaller diameter mandrel or other spooling structure. This may accordingly permit the use of actuators with reduced size, weight, and cost. However, it should be understood that the currently disclosed devices are not limited to any particular type of tether.
Turning to the figures, specific non-limiting embodiments are described in further detail. It should be understood that the various systems, components, features, and methods described relative to these embodiments may be used either individually and/or in any desired combination as the disclosure is not limited to only the specific embodiments described herein.
As noted above, in
In addition to the above, it should be understood that a spring used with the disclosed devices may correspond to any compliant structure capable of applying a desired force to a user's joint upon extension and/or compression. For example, as noted previously, appropriate types of springs may include, but are not limited to, one or more selected from the group of a tension spring, a torsional spring, a leaf spring, and a curved elongated structure. Exemplary embodiments of springs and their arrangement in a device are described in further detail below.
In
It should be understood that while the actuators and springs depicted in the above, embodiments are depicted as applying torques in various directions and are arranged on various sides of the joint and/or limb of a user, the applied torques and arrangements of these components relative to the joint and/or limb are not limited to only those shown. For example, in some embodiments, a spring may apply a torque to the joint to bias a foot to a toe down position and an associated actuator module may be operated to apply a torque to the joint to bias the foot to a toe up position. In such an embodiment, the spring may be located on a side and/or rear surface of the user's leg when worn in the actuator may be located on a front of the user's leg when worn. Accordingly, the current disclosure encompasses any number of variations regarding the specific combinations of torques and/or locations of the springs and actuators discussed herein. Additionally, the disclosure of antagonistic springs and actuators for use with assisting the movement of a joint of an individual may be applied to any appropriate joint even though the embodiments above are described relative to an ankle joint.
In addition to the relative positioning and operation of springs and actuators,
One or more sensors may be provided at the interface between a support 114 and an anchor 105. In some embodiments, a sensor 120 is disposed between the support mount 122 and the anchor mount 124. The sensor 120 may be fixedly coupled to the anchor mount 124, and the support mount 122 may attach directly to the sensor 120. That is, the support mount 122 may be directly connected to the sensor 120, and the sensor 120 may be directly connected to the anchor mount 124. The sensor 120 may be coupled to the support mount 122 and/or the anchor mount 124 using a fastener, press fit geometry, epoxy, adhesive, or any other suitable coupling. As such, in some embodiments, the support mount 122 may be indirectly coupled to the anchor mount 124 via the sensor 120. In some embodiments, the support mount 122 may be directly connected to the anchor mount 124, and the sensor 120 may be coupled to one or both of the support mount 122 and the anchor mount 124.
In some embodiments, the sensor 120 is a force sensor configured to measure forces exerted by the anchor 104 on the support 114 and/or forces exerted by the support 114 on the anchor 104. Signals from the sensor 120 may be used to calculate forces and/or torques associated with the support 114 and/or the anchor 104. Other types of sensors may be included at the interface between a support 114 and an anchor 104. For example, force and/or torque sensors may be integrated into the support 114, and/or a strain gauge 121 may be applied directly to the support 114. Alternatively or additionally, position sensors may be used to measure the deformation of the support 114. Because the support 114 may operate as a spring with a known stiffness, signals from the position sensors may be used to calculate forces and/or torques associated with the support 114. For example, a torque applied to the joint by the support 114 may be calculated using the known stiffness of the support 114 and the measured deformation of the support 114.
While much of the preceding description has referred to a user's ankle, calf, and foot, this is for illustrative purposes only. Accordingly, it should be understood that the device is disclosed herein may be applied to other joints and body portions for assisting motion of the corresponding joint. For example,
The guide 812 and/or the tether engaging portion 812a may include a low-friction material and/or coating configured to minimize wear on the tether 806. A low-friction material may also minimize a resistance to sliding motion between the tether 806 and the guide 812 and/or the tether engaging portion 812a. Non-limiting examples of low-friction materials include ceramics, plastics, and polished metals such as stainless steel, aluminum, brass, and copper with a suitably smooth surface to provide a desired low coefficient of friction for a desired application. Of course, other low-friction materials may be suitable, and the present disclosure is not limited to any specific material. In some embodiments, low-friction materials may include materials that, when in contact with a tether, are associated with a low coefficient of friction. In some embodiments, a coefficient of friction between a guide 812 (and/or a tether engaging portion 812a) and a tether 806 may be less than or equal to 0.5, 0.4, 0.3, 0.2, 0.1, or any other appropriate value. In some embodiments, a coefficient of friction between a guide 812 (and/or a tether engaging portion 812a) and a tether 806 may be greater than or equal to 0.01, 0.1, 0.2, 0.3, 0.4, or any other appropriate value. Combinations of the foregoing are also contemplated, including a coefficient of friction between a guide 812 (and/or a tether engaging portion 812a) and a tether 806 of between 0.01 and 0.5, 0.01 and 0.3, 0.01 and 0.1, and/or any other appropriate combination. Additionally or alternatively, bearings or other rolling elements may be integrated into the guide 812 and/or the tether engaging portion 812a to reduce wear on the tether 806.
In some embodiments, it may be desirable for the guide 812 to be configured to move in a direction substantially parallel to a length of the mandrel 810, such as an axial length of the mandrel. For instance, the guide may be moveably mounted on one or more rails 814 that extend in a direction parallel to an axial direction of the mandrel. In the embodiment specifically depicted in
As stated above, it may be desirable to wind only a single layer of tether around the mandrel because a tether that winds upon itself multiple times may experience increased fatigue, and may result in a higher motor torque due to changes in the applied moment arm as the tether is wound on top of itself on a relatively small mandrel. To achieve a single layer, a winding angle θ1 of the tether around the mandrel may be steep enough to make winding directional, but not so steep that the mandrel runs out of winding room. In some embodiments, a guide of an actuator engaged with a tether may provide a winding angle of Oi that is greater than or equal to any angle greater than 0° that ensures the rope winds in a single layer. Further the winding angle θ1 may be less than or equal to 80°. Combinations of the above noted ranges for the winding angle are contemplated including, for example, a winding angle between or equal to 4° and 80°. Further, a guide may maintain a winding angle within any other appropriate range of angles during operation. However, maintaining such a range, or any other suitable range, of angles may be difficult when the system is mounted on a user, as the entry angle θ2 of the tether may change constantly as a user moves about.
Referring to
As shown in
The above described tether enclosures may offer a number of benefits including, but not limited to: protecting users from abrasion and tangling with an exposed tether; protecting the inside of the actuator from environmental contaminants; and allowing the tether to be coated with a wet lubricant or dry lubricant, which can significantly improve tether lifetime, without exposing the user and surrounding environment to the lubricant. In addition, and embodiments in which the enclosure is elastic, the stiffness of the enclosure may be tailored to provide a certain amount of constant tension to the connected anchors used to hold the device on corresponding portions of a user's body when the device is worn. This initial tensioning of the enclosure may be desirable for keeping components in place. For example, the stiffness of the enclosure may be selected to provide tension that holds the anchors in place while not affecting the user's kinematics. In one such application, the enclosure may exert a tensile force of about 5 N to 10 N at about 50% elongation though other ranges both greater and less than those noted above are also contemplated depending on the application. Alternatively, the stiffness may be selected in order to have a measurable impact on user kinematics (e.g., an assistive torque during a power-off state), provide a preloading tension to smooth the application of force by the mandrel, or reduce the actuator's power requirements. Of course, embodiments in which the above-noted benefits are not provided, and/or different benefits are provided, by the disclosed devices are possible as the disclosure is not limited to providing these benefits in all instances. Several of these benefits are elaborated on further below.
In some embodiments, the primary portion 830 and the replaceable portion 840 may be engaged and/or disengaged manually. In some embodiments, components of the primary portion 830 and/or the replaceable portion 840 may aid in the engagement/disengagement of the two portions. For example, after an initial manual coupling phase of the two portions 830 and 840, motor 816 may be actuated to correlate motion of pulleys 817 and 818, which may serve as a final coupling phase to fully engage the two portions 830 and 840. In some embodiments, the primary portion and the replaceable portion may be coupled using a belt connecting two pulleys, sets of meshing gear teeth, and/or a spline coupling between two shafts. Of course, a primary portion and a replaceable portion may be appropriately coupled in other ways, and the disclosure is not limited in this regard.
A modular actuator 802 may additionally enable a user to modify the functionality of an actuation module, such as to adapt the actuation module to a particular function. For example, different replaceable portions 840 with different length tethers 806 may be selected to fit a range of user heights and sizes. Another modification would be to change the diameter of the timing pulleys 817 and 818 to change the gear ratio between the motor 816 and mandrel 810. This modification would enable a single actuation module with multiple replaceable portions 840 to be tailored to the specifications of a specific joint. For example, the ankle may require higher torque but lower speed, whereas the hip may require lower torque but higher speed. A set of replaceable portions 840 with different gear ratios could allow a single actuation module to accommodate both joints by replacing a first replaceable portion with a second replaceable portion. Changing the diameter of the mandrel 810 would have a similar effect to changing the gear ratio. Of course, other modifications may be made to an actuator 802 by replacing one replaceable portion 840 with another replaceable portion 840, and the disclosure is not limited to the modifications explicitly described herein.
As noted above, in some embodiments, a tether enclosure may be preloaded during use such that it provides a relatively constant low tension force to the attached anchors. Again, this may help to keep the anchors in place on a user's body even while the device is unpowered. This preloading of the device can also be used to reduce actuation jerk by smoothing the transition from an unloaded to a loaded state which may provide desirable effects on kinematics such as supporting knee control by opposing motion towards hyperextension. These conditions are shown in
Using the disclosed actuators and antagonistic springs, it is possible to provide a wide range of torques to a joint in various orientations of the joint during a motion cycle. For example, the torques applied by the actuator may be used to allow a full torque from a spring to be applied to an associated joint, to be partially applied to the joint, to cancel out a torque applied by the spring, and/or to apply a torque that is greater in magnitude, and opposite in direction, relative to the torque applied by the spring. Thus, with the ability to control torque delivered throughout the gait cycle, various actuation profiles may be applied to a joint by a device to provide various amounts of assistive torques during the various portions of the motion cycle.
In view of the above, it should be understood that the disclosed actuators and antagonistic springs may be used to apply any desired combination of positive, negative, and/or zero net torques to an associated joint during the various portions of a motion cycle without the use of antagonistic actuators. Further, such systems may provide desired failure and/or unpowered modes, where they may still provide a desirable assistance, such as torques to bias a foot towards a toe up position, even when operating in a passive unpowered or failure mode. The systems may also be operated to vary the amount of assistance provided to a user over time. For example, during initial therapy a system may provide a first amount of assistive torques during motion which may be reduced over time as a user's joint is rehabilitated and less assistance is needed. Alternatively, the system may provide assistive torques with a first magnitude during normal use and may be operated to provide lower assistive torques and/or zero net assistive torques during a physical therapy session. Accordingly, the disclosed systems provide a flexible platform for assisting motion of the joints of user in a number of different situations.
The above-described embodiments of the technology described herein can be implemented in any of numerous ways. For example, the embodiments may be implemented using hardware, software or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single computing device or distributed among multiple computing devices. Such processors may be implemented as integrated circuits, with one or more processors in an integrated circuit component, including commercially available integrated circuit components known in the art by names such as CPU chips, GPU chips, microprocessor, microcontroller, or co-processor. Alternatively, a processor may be implemented in custom circuitry, such as an ASIC, or semicustom circuitry resulting from configuring a programmable logic device. As yet a further alternative, a processor may be a portion of a larger circuit or semiconductor device, whether commercially available, semi-custom or custom. As a specific example, some commercially available microprocessors have multiple cores such that one or a subset of those cores may constitute a processor. Though, a processor may be implemented using circuitry in any suitable format.
Also, in some embodiments, the disclosed devices may include one or more input and output devices. These devices can be used, among other things, to present a user interface. Examples of output devices that can be used to provide a user interface include display screens for visual presentation of output and speakers or other sound generating devices for audible presentation of output. Examples of input devices that can be used for a user interface include keyboards, individual buttons, wirelessly connected devices, and pointing devices, such as mice, touch pads, and digital tablets. As another example, a device may receive input information through speech recognition or in other audible format.
Also, the various methods or processes outlined herein may be coded as software that is executable on one or more processors that employ any one of a variety of operating systems or platforms. Additionally, such software may be written using any of a number of suitable programming languages and/or programming or scripting tools, and also may be compiled as executable machine language code or intermediate code that is executed on a framework or virtual machine.
In this respect, the embodiments described herein may be embodied as a computer readable storage medium (or multiple computer readable media) (e.g., a computer memory, one or more floppy discs, compact discs (CD), optical discs, digital video disks (DVD), magnetic tapes, flash memories, RAM, ROM, EEPROM, circuit configurations in Field Programmable Gate Arrays or other semiconductor devices, or other tangible computer storage medium) encoded with one or more programs that, when executed on one or more computers or other processors, perform methods that implement the various embodiments discussed above. As is apparent from the foregoing examples, a computer readable storage medium may retain information for a sufficient time to provide computer-executable instructions in a non-transitory form. Such a computer readable storage medium or media can be transportable, such that the program or programs stored thereon can be loaded onto one or more different computing devices or other processors to implement various aspects of the present disclosure as discussed above. As used herein, the term “computer-readable storage medium” encompasses only a non-transitory computer-readable medium that can be considered to be a manufacture (i.e., article of manufacture) or a machine. Alternatively or additionally, the disclosure may be embodied as a computer readable medium other than a computer-readable storage medium, such as a propagating signal.
The terms “program” or “software” are used herein in a generic sense to refer to any type of computer code or set of computer-executable instructions that can be employed to program a computing device or other processor to implement various aspects of the present disclosure as discussed above. Additionally, it should be appreciated that according to one aspect of this embodiment, one or more computer programs that when executed perform methods of the present disclosure need not reside on a single computing device or processor, but may be distributed in a modular fashion amongst a number of different computers or processors to implement various aspects of the present disclosure.
Computer-executable instructions may be in many forms, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically the functionality of the program modules may be combined or distributed as desired in various embodiments.
The embodiments described herein may be embodied as a method, of which an example has been provided. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.
Further, some actions are described as taken by a “user.” It should be appreciated that a “user” need not be a single individual, and that in some embodiments, actions attributable to a “user” may be performed by a team of individuals and/or an individual in combination with computer-assisted tools or other mechanisms.
While the present teachings have been described in conjunction with various embodiments and examples, it is not intended that the present teachings be limited to such embodiments or examples. On the contrary, the present teachings encompass various alternatives, modifications, and equivalents, as will be appreciated by those of skill in the art. Accordingly, the foregoing description and drawings are by way of example only.
This application claims the benefit under 35 U.S.C. § 119(e) of U.S. provisional application Ser. No. 62/937,301, filed Nov. 19, 2019, the disclosure of which is incorporated by reference in its entirety.
This invention was made with government support under HD088619 awarded by National Institutes of Health. The government has certain rights in the invention.
Filing Document | Filing Date | Country | Kind |
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PCT/US2020/060825 | 11/17/2020 | WO |
Number | Date | Country | |
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62937301 | Nov 2019 | US |