Examination of human trajectory planning criterion based on signal-dependent noise

Abstract

Proposed optimization criteria to explain human multijoint arm motion include smoothness criteria and a minimum-variance criterion based on motor command-dependent noise (signal-dependent noise). It is reported that each of these criteria can effectively reproduce the human trajectory. This paper investigates the possibility that the minimum-variance criterion is included in trajectory planning. First, the relation between the hand trajectory and the final point variance is investigated for motion in the sagittal plane by a numerical experiment. Next, the corresponding relation is investigated by a behavioral experiment. Then, noise is added to the motor command as a simulation, and a behavioral experiment is performed to investigate the relation between the change of the trajectory and the variance. The experimental result suggests the possibility that the minimum-variance criterion is used in trajectory planning. However, it is difficult to account for the human arm motion in the sagittal plane by using only the minimum-variance criterion. The above results seem to indicate that both the smoothness criterion and the minimum-variance criterion based on signal-dependent noise are used in human arm trajectory planning. © 2005 Wiley Periodicals, Inc. Syst Comp Jpn, 36(14): 32–43, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20365