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Abstract
This thesis presents quantitative measures of mechanical energy of the human upper limbs. It compares the efficacy of 20 working-age people and three people using a powered below-elbow prosthesis during six activities of daily living (ADL's).
The method collects demographic and anthropometric characteristics and records the motions of three markers placed on each of the upper arms, forearms, hands and upper trunk using a 3-camera VICON 140™ system. With mass and moment of inertia estimates, potential and kinetic segmental energies are calculated by sample (60 Hz), and on average, over ADL. Qualitative data are recorded during tasks by video and questionnaires on perceived task difficulty, and preferred accomplishment methods.
Average mechanical energy summed over upper limb segments during ADL's provides an overall measure of mechanical energy, allowing comparisons across subjects and activities. However, long data gaps cannot be reliably filled. Also average potential energy varies up to 369 times that of kinetic energy. A simplified algorithm estimates mechanical energy using potential energy based on only two markers per segment. Data from non-prosthesis users show a highly significant interaction of task and arm dominance, while energy measures for the prosthesis users were lower on the nondominant arm (prosthesis) than on the dominant arm. Prosthesis users used more consistent methods and movements, but perceived task difficulty more extremely.
This method provides a quantitative tool to study the potential and actual method efficacy of working-age populations using upper limb prostheses while accomplishing working tasks. The results could be used to improve prosthesis design and use, leading to a reduction in fatigue and repetitive strain injuries.
