Publications by authors named "Amanda H Shultz"

This paper describes the development of a controller for a powered ankle prosthesis that is intended to provide appropriate biomechanical behavior for walking on both even and uneven terrain without having to explicitly detect local slope to do so. In order to inform development of the controller, the authors conducted a small study of five healthy subjects walking on even and uneven terrain. Data from the healthy subject study were used to formulate behavioral models for the healthy ankle, which were then implemented as controller behaviors in the powered prosthesis prototype and comparatively assessed on an amputee subject.

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A successful walking gait with a powered prosthesis depends heavily on proper timing of power delivery, or push-off. This paper describes a control approach which provides improved walking on uneven terrain relative to previous work intended for use on even (level) terrain. This approach is motivated by an initial healthy subject study which demonstrated less variation in sagittal plane shank angle than sagittal plane ankle angle when walking on uneven terrain relative to even terrain.

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This paper describes a control approach that provides walking and standing functionality for a powered ankle prosthesis, and demonstrates the efficacy of the approach in experiments with a unilateral transtibial amputee subject. Both controllers incorporate a finite-state structure that emulates healthy ankle joint behavior via a series of piecewise passive impedance functions. The walking controller additionally modifies impedance parameters based on estimated cadence, while the standing controller modulates the ankle equilibrium angle in order to adapt to the ground slope and user posture, and the supervisory controller selects between the walking and standing controllers.

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This paper describes a walking controller implemented on a powered ankle prosthesis prototype and assessed by a below-knee amputee subject on a treadmill at three speeds. The walking controller is a finite state machine which emulates a series of passive impedance functions at the joint in order to reproduce the behavior of a healthy joint. The assessments performed demonstrate the ability of the powered prosthesis prototype and walking controller to reproduce essential biomechanical aspects (i.

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This paper presents a running control architecture for a powered knee and ankle prosthesis that enables a transfemoral amputee to run with a biomechanically appropriate running gait and to intentionally transition between a walking and running gait. The control architecture consists firstly of a coordination level controller, which provides gait biomechanics representative of healthy running, and secondly of a gait selection controller that enables the user to intentionally transition between a running and walking gait. The running control architecture was implemented on a transfemoral prosthesis with powered knee and ankle joints, and the efficacy of the controller was assessed in a series of running trials with a transfemoral amputee subject.

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Recent advances in robotics technology are enabling the emergence of robotic leg prostheses that can emulate the full biomechanical functionality of the healthy limb. The behavior of such prostheses is software-controllable, in an analogous manner to the way in which the central nervous system controls the human musculoskeletal system. Although these prostheses have the capability of reproducing the biomechanical behavior of the healthy limb, their ability to do so is a function of how well the prosthesis control system coordinates the movement of the leg with the movement of the user.

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