Variable stiffness devices and methods of their use are provided. In some embodiments, a variable stiffness device comprises an inner member defining a compartment for receiving an actuating fluid; an outer member disposed around the inner member; and a granular medium disposed between the inner member and the outer member; wherein the inner member is being moveable in a radial direction from a relaxed state to an expanded state by introducing the actuating fluid into the compartment of the inner member to compress the granular medium against the outer member to increase the stiffness of the device.

An actuator device that includes a conducting material and at least one fuse incorporated into the conducting material is disclosed. The at least one fuse may stop current flow for temperatures above a specific temperature. The actuator device may also include a series of electronics that determine whether the actuating device has blown the at least one fuse.

An upper extremity prosthesis may include a prosthetic hand including a prosthetic thumb having a base and a tip, and a prosthetic index finger having a base and a tip. Actuators may be coupled to the upper extremity prosthesis. Prosthetic flexion tendons may have first ends operably coupled to the actuators and second ends coupled to the tips of the thumb and the index finger. Biasing systems may be operably coupled to the prosthetic thumb and the index finger. Upon actuation of the actuators in a first direction, the prosthetic flexion tendons cause the thumb and index finger to flex. Upon actuation of the linear actuators in a second direction opposite the first direction, the biasing systems cause the thumb and index finger to extend.

A system and method for creation and function of an advanced prosthetic hand includes: a base palm, comprising the primary body of the prosthetic hand; a set of actuating digits, wherein each actuating digit is connected to the palm; a sleeve, connected to the palm, providing an interface; a sensor system, comprising sensors integrated on a subset of the set of actuating digits; and a feedback system, connected to the sensor system enabling sensory feedback from the sensor system. In preferred variations, the base palm comprises, at least partially, a carbon-fiber shell. The system may further include a set of water sealing elements integrated into the prosthetic hand. The system functions as a hand prosthesis with actuating digit and hand components.

Artificial muscles comprising a body of dielectric elastomer, wherein the body contains a pair of microfluidic networks are presented. Each microfluidic network includes a plurality of channels fluidically coupled via a manifold. The channels of the microfluidic networks are interdigitated and filled with conductive fluid such that each set of adjacent channels functions as the electrodes of an electroactive polymer (EAP) actuator. By using the manifolds as compliant wiring to energize the electrodes, artificial muscles in accordance with the present disclosure mitigate some or all of the reliability problems associated with prior-art artificial muscles.

An elongate fiber artificial muscle includes or consists of an elongate carbon or glass fiber and at least a partial coating of a polymer, and preferably a full shell coating to form a core-shell arrangement, that is volumetrically responsive to thermal changes or to moisture changes. Additional elongate fiber artificial muscles of the invention include a plurality of elongate carbon or glass fibers that are infiltrated between the fibers with a polymer that is volumetrically responsive to thermal changes or to moisture changes. In a fabrication method, the rheology (flow characteristic) of a polymer precursor is adjusted with solvent so it is less viscous. A fiber or plurality of fibers (pre-twisted or untwisted), such as a tow is dipped in the polymer precursor. The fiber or fibers is then pulled out of the polymer precursor and hung to allow polymer to distribute and then cured and can be twisted to coil prior to curing. A model is provided to fabricate elongate fiber artificial muscle with specific characteristics based upon a thermal or moisture expansion coefficient of the polymer, its elongation capability percentage before flaking or breaking, and its elastic modulus.

Rate-dependent, elastically-deformable devices according to various embodiments can be stretched and recovered at low elongation rates. Yet they become stiff and resistive to stretching at high elongation rates. These device can be utilized in orthotics, braces, and circulation-enhancing compression garments for the prevention of injury, promotion of personal health, and/or enhancement in human performance. The rate-responsive properties of the devices are critical performance enablers, as they allow the devices to provide a unique balance of comfort and performance that cannot be achieved with conventional, passive straps, braces, and compression garments.

An orthotic device is disclosed. The orthotic device may be adapted to be inserted into a shoe to enable the foot to replicate normal motion so that the user regains substantially normal operation of the foot. The orthotic device may have a frame system formed of a lightweight supportive material and configured to extend along at least the bottom of the user's foot, and an electronically actuated muscle operatively connected to the frame system for expanding and contracting at predetermined levels to adjust the inclination of the user's foot and mimic movement of the foot, when functioning normally. The orthotic device may also have a controller operatively connected to the muscle for transmitting signals corresponding to the predetermined levels to the muscle, and a sensor controlled by the user for actuating the muscle.

An approximation method and system are provided for more quickly controlling a prosthetic or other device by reducing computational processing time in a muscle model that can be used to control the prosthetic. For a given muscle, the approximation method can quickly compute polynomial structures for a muscle length and for each associated moment arms, which may be used to generate a torque for a joint position of a physics model. The physics model, in turn, produces a next joint position and velocity data for driving a prosthetic. The approximation method expands the polynomial structures as long as expansion is possible and sufficiently beneficial. The computations canbe performed quickly by expanding the polynomial structures in a way that constrains the muscle length polynomial to the moment arm polynomial structures, and vice versa.

A system and method for controlling a device, such as a virtual reality (VR) and/or a prosthetic limb are provided. A biomimetic controller of the system comprises a signal processor and a musculoskeletal model. The signal processor processes M biological signals received from a residual limb to transform the M biological signals into N activation signals, where M and N are integers and M is less than N. The musculoskeletal model transforms the N activation signals into intended motion signals. A prosthesis controller transforms the intended motion signals into three or more control signals that are outputted from an output port of the prosthesis controller. A controlled device receives the control signals and performs one or more tasks in accordance with the control signals.