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Isometric force tracking ability of humans


In the experimental setup, a human subject tracks visual images of force traces displayed on the monitor by applying appropriate normal forces through a fingerpad that is in contact with a force sensor (Srinivasan and Chen, 1993). In these experiments, the finger moves by only fractions of a mm, thus approximating isometric muscular contraction conditions. We had completed one set of experiments on such force tracking last year, and now we have expanded the range of target forces and their frequency. During tracking constant and sinusoidal force targets (three subjects with 3 trials per stimulus), the mean absolute error increased with constant force magnitude, target sinusoid frequency and amplitude. The errors for a sinusoid of a given amplitude are 5 to 40 times higher than those for constant force targets with the same magnitude. Even at relatively low frequency of 2 Hz, the errors can be higher than 50% of the sinusoid amplitude at all amplitudes.

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Last Updated: May 8, 2002 1:45 PM Comments: David Schloerb