The Contribution of Visual Feedback to Movement Control in a Visuomotor Tracking Task

Master thesis (2014)

Authors

Contributors

E. De Vlugt (mentor)
Programme
BMD (Mechanical, Maritime and Materials Engineering) (TU Delft)
Copyright: © 2014 Dobbe, L.R.M.
Motor control System identification Visual feedback Sipe Physiological modeling
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Published Date

02-12-2014

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Programme

BMD

Abstract

The aim of this study was to determine if and how specific characteristics of visual information influence the motor control strategy adopted during a visuomotor tracking task. To this end, twenty healthy subjects and two stroke patients were measured. Changes in wrist joint admittance (i.e., wrist rotations due to external forces) due to specific manipulations of the visual scenery related to task demands (i.e., tolerance, velocity, preview; experiment 1) and related to presentation of visual information (i.e., gain, optical flow density; experiment 2) were quantified using System Identification and Parameter Estimation (SIPE) techniques in order to distinguish between continuous feedback, intermittent feedback and anticipatory feedback control strategies. To this end, a linear physiological model comprising short-latency muscle spindle feedback \'and long-latency visual position feedback was fitted to the experimental data. To study control adaptability, the potential of a linear time invariant (LTI) technique to analyze time variant (TV) control behavior was explored. In both experiments, manipulations of the visual information elicited significant changes in intrinsic and reflexive neuromuscular properties and use of visual feedback. The findings suggest that humans flexibly adapt their use of visual feedback between continuous feedback and intermittent feedback control, dependent of demands on task precision and movement velocity. Anticipatory feedback control was dependent on the amount of future task information available, but was suppressed by high task demands and increased when movements were visually amplified. LTI models can successfully be deployed for the analysis of TV control behavior in tracking tasks, provided that actual movement amplitudes are small. It is concluded that the discussed methods yield potential in the identification of motor control adaptability for the use in diagnostics of movement disorders.