Abstract: A variable stiffness actuator comprises a flexure plate which comprises a first cantilevered beam that extends inwards from an outer periphery of the flexure plate. A housing and the flexure plate rotatable about a common joint axis. A first contactor is pivotably secured at a revolute joint to the housing. The first contactor rotates about the revolute joint at a first rotation axis. The first rotation axis offset on the housing from the joint axis. The first contactor engages the first cantilevered beam at a variable angle about the rotation axis to adjust a stiffness of a mechanical connection between the flexure plate and the housing.

Abstract: An ankle prosthesis comprises a foot prosthesis. A lower ankle is pivotably secured to the foot prosthesis at an ankle joint. An upper ankle is connected to the lower ankle in a manner that permits vertical movement of the upper ankle relative to the lower ankle. A coupling spring is biased in an extended condition. The coupling spring is connected at a first end to the upper ankle. A second end of the coupling spring is movable in a first condition which is engaged to the lower ankle and in a second condition engaged to the foot prosthesis. Energy is stored in compression of the coupling spring when the coupling spring is in the first condition and energy is released from the coupling spring when the coupling spring is in the second condition.

Abstract: An ankle prosthesis comprises a foot prosthesis. A lower ankle is pivotably secured to the foot prosthesis at an ankle joint. An upper ankle is connected to the lower ankle in a manner that permits vertical movement of the upper ankle relative to the lower ankle. A coupling spring is biased in an extended condition. The coupling spring is connected at a first end to the upper ankle. A second end of the coupling spring is movable in a first condition which is engaged to the lower ankle and in a second condition engaged to the foot prosthesis. Energy is stored in compression of the coupling spring when the coupling spring is in the first condition and energy is released from the coupling spring when the coupling spring is in the second condition.

Abstract: A variable stiffness actuator comprises a flexure plate which comprises a first cantilevered beam that extends inwards from an outer periphery of the flexure plate. A housing and the flexure plate rotatable about a common joint axis. A first contactor is pivotably secured at a revolute joint to the housing. The first contactor rotates about the revolute joint at a first rotation axis. The first rotation axis offset on the housing from the joint axis. The first contactor engages the first cantilevered beam at a variable angle about the rotation axis to adjust a stiffness of a mechanical connection between the flexure plate and the housing.

Abstract: In one embodiment, a selectable-rate spring comprises a flexure bar connected to a rotatable shaft, the flexure bar having at least one arched portion. The selectable-rate spring also includes at least one rotational contactor connectable to a link member, wherein the rotational contactor rotates about an axis while maintaining contact with the arched portion of the flexure bar. As the rotational contactor rotates, it changes the connection stiffness between the rotatable shaft and the link member.

Abstract: In one embodiment, a selectable-rate spring comprises a flexure bar connected to a rotatable shaft, the flexure bar having at least one arched portion. The selectable-rate spring also includes at least one rotational contactor connectable to a link member, wherein the rotational contactor rotates about an axis while maintaining contact with the arched portion of the flexure bar. As the rotational contactor rotates, it changes the connection stiffness between the rotatable shaft and the link member.

Abstract: Disclosed are passive lower limb prosthetic devices comprising at least a two degree of freedom mechanism and a network of compression springs.

Abstract: Disclosed are passive lower limb prosthetic devices comprising at least a two degree of freedom mechanism and a network of compression springs.

Abstract: A method and apparatus for installing a part such as a gear into an assembly such as a gear set with low-stiffness and low inertia comprises an insertion mechanism that is connected to a controller at one end, and that is connected to the part at a second end. In one embodiment, the insertion mechanism at least permits rotational compliance about the z axis with respect to the controller independent of compliance in the x, y, and z axes to permit the part to mesh with the assembly during the installation process. In another embodiment, the insertion mechanism is compliant only along the x, y, and z axes.

Abstract: A mechanism capable of achieving an arbitrarily specified spatial compliant behavior is presented. The mechanism is a parallel connection of multiple individual elastic components that connect a support body to a single compliantly floated body. Each elastic component is, in itself, a low friction 6 degrees of freedom (DOF) mechanism that provides compliant constraint along and/or about a single axis. The elastic components are of three functional types: 1) a “line spring” which resists only translation along its axis, 2) a “torsional spring” which resists only rotation about its axis, and 3) a “screw spring” which resists a specified combination of translation along and rotation about its axis. Through proper selection of the connection geometry, spring constant, and functional type of each elastic component, a spatial compliant mechanism capable of passive force guidance is realized.

Abstract: A mechanism capable of achieving an arbitrarily specified spatial compliant behavior is presented. The mechanism is a parallel connection of multiple individual elastic components that connect a support body to a single compliantly floated body. Each elastic component is, in itself, a low friction 6 degrees of freedom (DOF) mechanism that provides compliant constraint along and/or about a single axis. The elastic components are of three functional types: 1) a "line spring" which resists only translation along its axis, 2) a "torsional spring" which resists only rotation about its axis, and 3) a "screw spring" which resists a specified combination of translation along and rotation about its axis. Through proper selection of the connection geometry, spring constant, and functional type of each elastic component, a spatial compliant mechanism capable of passive force guidance is realized.