title: Feedback control of limb stiffness and scaled phase invariance properties of skilled high-speed arm flexion movements of a loaded manipulator.
abstract: In this and a previous experiment it has been observed that subjects produce innervation patterns (EMG) that are load specific, i.e., they produce concentration patterns for movements made with inertial loads and triphasic patterns for movements made with elastic loads. The protocol of these experiments prevented any adaptive responses to the load changes, therefore, it was assumed that pattern matching to load type was a real time updating response of the peripheral feedback systems. This updating response was assumed to be a mechanism for fine tuning the muscle torque by regulation of the mechanical impedance (stiffness) of the limb. Using a standard equation of motion, it was shown that the velocity is equal to the ratio of the muscle torque to the mechanical impedance. Substitution of this ratio for the ordinate of the scaled phase diagrams was then suggested as a real time updating mechanism to account for the scaled phase invariance recorded in this experiment and in the experiment reported by Ruitenbeek, J.C., Biol. Cybernetics 51 (1984) 11-20.
authors.affiliation: Department of Physical Education, San Diego State University, CA 92182.
authors.forename: C
authors.initials: C
authors.lastname: Richardson
authors.forename: R W
authors.initials: RW
authors.lastname: Simmons
mesh_terms: D001696:Biomechanical Phenomena; D004576:Electromyography; D005121:Extremities / Q000502:physiology*; D005246:Feedback / Q000502:physiology; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D012399:Rotation; D013314:Stress, Mechanical