Estimation of a human planned trajectory from a measured trajectory

Abstract

AbstractThe general view of human motion is that it is realized by combining feedforward control based on a planned trajectory and feedback control for correction. Thus, in order to analyze the motion control mechanism, these two components must be separately extracted. One possible approach is to estimate the trajectory planned before performance from the realized trajectory, including the correction, as obtained by measurement. This paper proposes a method of estimating the planned trajectory from the actually measured finger trajectory in two‐point reaching motion. The following two assumptions are made in the estimation of the planned trajectory. (1) Since there is a time delay in the feedback loop, the measured trajectory immediately after the start of motion can be considered to be the planned trajectory. (2) The human planned trajectory is represented as the minimum command torque change trajectory. Based on these assumptions, the entire planned trajectory can be determined from the measured trajectory immediately after the start of the motion. Assuming that by sufficient training of the reaching motion in the state without vision, the subject can move the hand to a target with little correction, this motion is measured and the planned trajectory is estimated. The measured trajectory and the planned trajectory are very close except for the neighborhood of the target point. It is thus shown that the planned trajectory can be estimated by the method proposed in this study. © 2006 Wiley Periodicals, Inc. Syst Comp Jpn, 37(9): 1– 11, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20536