Dudley S. Childress

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The non-disabled human ankle joint was examined during walking in an attempt to determine overall system characteristics for use in the design of ankle prostheses. The hypothesis of the study was that the quasi-stiffness of the ankle changes when walking at different walking speeds. The hypothesis was examined using sagittal plane ankle moment versus ankle(More)
This research was devoted to an investigation of the practicality and potential effectiveness of applying the concept of extended physiological proprioception (EPP) to the control of upper-limb prostheses. The purpose of this study was to verify that EPP control, implemented by coupling prosthesis function to residual shoulder motion in a position-servo(More)
Differences in pelvic obliquity between small groups of persons with unilateral lower limb amputation and subjects without amputation were analyzed. Kinematic walking data were collected as six males with transtibial amputation and three males with transfemoral amputation walked over a range of speeds. The pelvic obliquity patterns and amplitudes from the(More)
To achieve significant improvement in the function of electric-powered, upper-limb prostheses, we believe it is necessary to develop better control interfaces with inherent sensory feedback. Small cineplasties, or other surgical procedures that also externalize the force and excursion of a muscle, could potentially provide this superior control. Connecting(More)
This study investigated the temporal characteristics of gait initiation and gait termination. Ten nondisabled adult volunteers and ten people with unilateral transtibial limb loss performed starting and stopping for slow, normal, and fast walking speeds. We used kinematic and anthropomorphic data to determine the body center of mass (BCOM) position of each(More)
A series of experiments was performed to measure the relationships between the integrated surface EMG and the mechanical state of the cineplastic biceps muscle of one subject. The muscle was studied during static and dynamic isometric contractions at different muscle lengths and during constant velocity isotonic contractions at different loads. The(More)
OBJECTIVE To determine the effect of stance-phase knee flexion on the trunk's vertical displacement in normal walking. SUBJECTS Three able-bodied adult male volunteers. DESIGN Kinematic data describing the joint centers and joint angles of the legs and pelvis were collected from the subjects. The subjects walked at four target speeds (range,(More)
The quasi-static response of bulk muscular tissue to indentation was measured on the posterior lower legs of living human subjects. No residual limbs were tested; all subjects had intact lower limbs. For loads up to 7.0 N on an 8.0 mm diameter flat-tipped indentor, the response was repeatable without prior 'preconditioning'. The data at any test location(More)
This study investigated the effects of shoe heel height on the rollover characteristics of the biologic ankle-foot system. Ten nondisabled adult female volunteers walked using three pairs of shoes with varying heel heights and at three walking speeds with each pair of shoes. Kinematic and kinetic data needed to calculate the rollover shapes of the(More)
The Shape&Roll prosthetic foot was used to examine the effect of roll-over shape arc length on the gait of 14 unilateral trans-tibial prosthesis users. Simple modifications to the prosthetic foot were used to alter the effective forefoot rocker length, leaving factors such as alignment, limb length, and heel and mid-foot characteristics unchanged.(More)