A characterization of the mechanical impedance of human hands

author:Aram Zaven Haijan
adviser:Robert D. Howe
degree: Ph.D.
institution: Harvard University

Previous analyses of the mechanical impedance of the upper limb have often focused either on quasi-static stiffness measurements or arm level motions and dynamics. In this thesis, we consider hand impedance with the specific goal of identifying the impedance at short time scales associated with rapidly executed dexterous tasks. The first study describes experimental measurements of the mechanical impedance at the index finger tip for extension and abduction of the metacarpophalangeal joint of the index finger. The second study enlarges the scope to include the characterization of the impedance of a pinch grasp of a rigid object between the thumb and index finger. Next, we develop a biomechanical model to represent one portion of a fast drumming task using impedance modulation of a pinch grasp. Through the model, we characterize the mechanism and strategy by which drummers successfully execute rapid drum rolls. The model is subsequently validated by predicting drum roll durations of real drummers. The final study describes an experiment which recreates the human drumming strategy through the design and fabrication of a robot drummer. We conclude by discussing impedance analysis relevant in other tasks, and propose directions for future endeavor.

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