16.423J/HST515J Aerospace Biomedical Engineering and Life Support Prof. Newman Robot / Human Comparisons (how inhumane) Table I presents some of the elements of robotic and animal movement systems neatly compared for your viewing pleasure. Table I. Comparison of Movement Control Systems in the Robot and Human Communication Speed Control System Effectors Effector Directionality Transmission Degree of Freedom Control Design Transducers ROBOT wires 3 x 10 8 m/sec computer motors (linear) push or pull gears/linkages (precise geometry <10 closed loop position velocity acceleration HUMAN 10 5 -10 6 axons 10-100 m/sec brain/spinal cord 400 + muscles (non-linear) pull only joints/tendons (nightmare geometry ~100 closed loop position (Muscle spindle) velocity (Muscle spindle) force (Golgi Tendon Organ) Table II Motor Unit Properties (adapted from Henneman, 1980). Red Muscle Fibers White Muscle Fibers Number of motor units many few Number of muscle fibers few many per motor unit Axon diameter small large Tetanic tension small larg Contraction speed slow rapid Fatigue slow rapid Metabolism aerobic anaerobic Blood supply rich sparse