Dynamic primitives in constrained action: systematic changes in the zero-force trajectory

Abstract

Control using primitive dynamic actions may explain why human performance is superior to robots despite seemingly inferior “wetware”; however, this also implies limitations. For a crank-turning task, this work quantified two such informative limitations. Force was exerted even though it produced no mechanical work, the underlying zero-force trajectory was roughly elliptical, and its orientation differed with turning direction, evidence of oscillatory control. At slow speeds, speed variability increased substantially, indicating intermittent control via submovements.