ABSTRACT
The human nervous system is capable of simultaneous and integrated control of 100 to 150 mechanical degrees of freedom of movement in the body via tensions generated by about 700 muscles. In its widest context, movement is carried out by a sensory-motor system comprising multiple sensors (visual, auditory, proprioceptive), multiple actuators (muscles and skeletal system), and an intermediary processor which can be summarized as a multiple-input multiple-output nonlinear dynamic time-varying control system. This grand control system comprises a large number of interconnected processors and sub-controllers
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at various sites in the central nervous system of which the more important are the cerebral cortex, thalamus, basal ganglia, cerebellum, and spinal cord. It is capable of responding with remarkable accuracy, speed (when necessary), appropriateness, versatility, and adaptability to a wide spectrum of continuous and discrete stimuli and conditions. Certainly, by contrast, it is orders of magnitude more complex and sophisticated than the most advanced robotic systems currently available — although the latter also have what are often highly desirable attributes such as precision and repeatability and a much greater immunity from factors such as fatigue, distraction, and lack of motivation!
