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Propagation of impulsive shock waves in the human musculoskeletal system
Abstracts--International Societyof BiomechanicsXII Congress1989 A TELESCOPING EFFECT OF
IMPACTS
THE
HUMAN
1095
HAND AND FOREARMDURING HIGH ENERGY
M. Voigt. Laboratory for functional anatomy, Department of anatomy, University of Copenhagen, Blegdamsvej 3, DK2200 Copenhagen N. A karate punch very similar to the boxer’s straight right was studied in 10 well trained karate students. A punching dynamometer was and calibrated with a series of controlled constructed (accelerometry) impacts. Punches were recorded by stroboscopic photography (100 Hz), high speed filming (500 Hz) and a triaxial force plate. Results: peak impact force: 3334 N (2345 - 4866 N), maximal speed of the hand before effective mass from calibrated impact: 9.5 m/set (8.2 - 10.7 m/set), punching dynamometer: 1.4 kg (1.0 - 2.2 kg), effective mass from stroboscopic recordings: 4,0 kg (2.5 - 4.5 kg). The collisions showed (coefficient of inelastic characteristics restitution, e = 0.3 (O.OThe shape of the force curves during the impacts of the 0.4)). unprotected hand was characterized by an asymmetrical shape (fast slow descending part) and by a relatively long impact ascending part, curve showed time (average 15 msec). The descending part of the force pattern.3 irlith 1 3 deflections. It is suggested repeatable waweforrn that the hand and forearm act as a series of masses of different size connected with springs and viscoelastic dam;re rs, and with changing characteristics of the springs and dampers, depending on the tension in the muscles and the fi.1 i I’I~: .~f fluid compartments.
PROPAGATION OF IMPULSIVE SHOCK WAVES IN THE HUMAN MUSCULOSKELETAL SYSTEM Arkady S. Voloshin Department of Mechanical Engineering and Mechanics and Institute for Biomedical Engineering Lehigh University, Bethlehem, PA 18015, USA Several studies have associated impulsive loading resulting from gait with excessive fatigue and progressive damage to the natural shock absorbersof the human locomotor system. Significant reduction of the injurious effects of gait induced shock waves are contingent upon the development of accurate methods to quantify these waves and the effect of various shock absorbing devices (footwear, insoles, etc.) on the human body. This study utilizes the non-invasive, in-vivo methodology for the acquisition of real-time data of the impulsive shock waves at particular locations of the human musculoskeletal system. The analysis of the acceleration values attained at the measurement points on the bodies of the 40 individuals tested show that the heel strike induced shock wave is gradually attenuated by various shock absorbersof the human musculoskeletal systemon its way toward the skull. It is attenuated by 50% at the tibial tuberosity, by 80% - at the hip area and by 88% at the forehead. While all of the 40 subjects were healthy individuals, the data acquired revealed unbalanced shock attenuational capacitiesfor 22 of the subjectstested, the main reason for this discrepancywas that one leg was more developed than the other. This consideration was confiied when all of the 22 “unbalanced” subjects acknowledged that they preferred to use the leg with the better shock attenuational capacity.
HUMAN JOINT HYBRID CONTROL MODEL
Miomir Vukobratovid and Vladimir IvanEevic’ Mihajlo Pupin Institute, Belgrade, Yugoslavia Yugoslav Institute for Sports Medicine, Belgrade A solution of the single human extremity joint hybrid control is proposed in the form of the 13.th order linear differential Cauchy's system. A joint with predominantly one degree of freedom is selected (elbow or knee). Basic energy is obtained by efferent electrical stimulation of the neuro-
musular end-plates of the natural actuator in the given joint. Simultaneously and constantly stimulation of both the m.agonist and m.antagonist of the desired movement is performed, whereby m.agonist is stimulated by Heaviside's rectangular input and m.antagonist by an exponential input. External energy is supplied by an electromechanical actuator of Institute "Mihailo Pupin", already realized for the active orthosis.
IMPACTS
THE
HUMAN
1095
HAND AND FOREARMDURING HIGH ENERGY
M. Voigt. Laboratory for functional anatomy, Department of anatomy, University of Copenhagen, Blegdamsvej 3, DK2200 Copenhagen N. A karate punch very similar to the boxer’s straight right was studied in 10 well trained karate students. A punching dynamometer was and calibrated with a series of controlled constructed (accelerometry) impacts. Punches were recorded by stroboscopic photography (100 Hz), high speed filming (500 Hz) and a triaxial force plate. Results: peak impact force: 3334 N (2345 - 4866 N), maximal speed of the hand before effective mass from calibrated impact: 9.5 m/set (8.2 - 10.7 m/set), punching dynamometer: 1.4 kg (1.0 - 2.2 kg), effective mass from stroboscopic recordings: 4,0 kg (2.5 - 4.5 kg). The collisions showed (coefficient of inelastic characteristics restitution, e = 0.3 (O.OThe shape of the force curves during the impacts of the 0.4)). unprotected hand was characterized by an asymmetrical shape (fast slow descending part) and by a relatively long impact ascending part, curve showed time (average 15 msec). The descending part of the force pattern.3 irlith 1 3 deflections. It is suggested repeatable waweforrn that the hand and forearm act as a series of masses of different size connected with springs and viscoelastic dam;re rs, and with changing characteristics of the springs and dampers, depending on the tension in the muscles and the fi.1 i I’I~: .~f fluid compartments.
PROPAGATION OF IMPULSIVE SHOCK WAVES IN THE HUMAN MUSCULOSKELETAL SYSTEM Arkady S. Voloshin Department of Mechanical Engineering and Mechanics and Institute for Biomedical Engineering Lehigh University, Bethlehem, PA 18015, USA Several studies have associated impulsive loading resulting from gait with excessive fatigue and progressive damage to the natural shock absorbersof the human locomotor system. Significant reduction of the injurious effects of gait induced shock waves are contingent upon the development of accurate methods to quantify these waves and the effect of various shock absorbing devices (footwear, insoles, etc.) on the human body. This study utilizes the non-invasive, in-vivo methodology for the acquisition of real-time data of the impulsive shock waves at particular locations of the human musculoskeletal system. The analysis of the acceleration values attained at the measurement points on the bodies of the 40 individuals tested show that the heel strike induced shock wave is gradually attenuated by various shock absorbersof the human musculoskeletal systemon its way toward the skull. It is attenuated by 50% at the tibial tuberosity, by 80% - at the hip area and by 88% at the forehead. While all of the 40 subjects were healthy individuals, the data acquired revealed unbalanced shock attenuational capacitiesfor 22 of the subjectstested, the main reason for this discrepancywas that one leg was more developed than the other. This consideration was confiied when all of the 22 “unbalanced” subjects acknowledged that they preferred to use the leg with the better shock attenuational capacity.
HUMAN JOINT HYBRID CONTROL MODEL
Miomir Vukobratovid and Vladimir IvanEevic’ Mihajlo Pupin Institute, Belgrade, Yugoslavia Yugoslav Institute for Sports Medicine, Belgrade A solution of the single human extremity joint hybrid control is proposed in the form of the 13.th order linear differential Cauchy's system. A joint with predominantly one degree of freedom is selected (elbow or knee). Basic energy is obtained by efferent electrical stimulation of the neuro-
musular end-plates of the natural actuator in the given joint. Simultaneously and constantly stimulation of both the m.agonist and m.antagonist of the desired movement is performed, whereby m.agonist is stimulated by Heaviside's rectangular input and m.antagonist by an exponential input. External energy is supplied by an electromechanical actuator of Institute "Mihailo Pupin", already realized for the active orthosis.