Publication: Performance limitations from delay in human and mechanical motor control

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Title	Performance limitations from delay in human and mechanical motor control
Authors/Editors*	J. Wu, D. Beamish, S. Bhatti, Z. Jing
Where published*	Biological Cybernetics
How published*	Journal
Year*	2008
Volume	0340-1200 (Print) 1432-0770 (Online)
Number
Pages
Publisher	Springer Berlin/Heidelberg
Keywords	Fitts' law - Psychomotor delay-Motor performance-Motor control-Neurodynamics
Link	http://www.springerlink.com/content/k0rq0634835754j3/?p=ade66c7aba4d4ceaad00eea37d67ca7a&pi=1
Abstract	We discuss natural limitations on motor performance caused by the time delay required for feedback signals to propagate within the human body or mechanical control systems. By considering a very simple delayed linear servomechanism model, we show there exists a best possible speed-accuracy trade-off similar to Fittsâ law that cannot be exceeded when delay is present. This is strictly a delay effect and does not occur for the ideal case of instantaneous feedback. We then examine the performance of the vector integration to endpoint (VITE) circuit as a model of human movement and show that when this circuit is generalized to include delayed feedback the performance may not exceed that of the servomechanism with an equal delay. We suggest the existence of such a limitation may be a ubiquitous consequence of delay in motor control with the implication that the index of performance in Fittsâ law cannot arbitrarily large.