Trial-to-Trial Nonlinear Dynamics of Human Movements

Project: Research project

Project Details


This interdisciplinary research program is focused on the development and application of a new class of nonlinear dynamical system inspired by the study of repeated precision human movements. The fundamental qualitative dynamics of these systems will be examined. Our approach is based on a novel definition of movement tasks in terms of goal functions, which encode the interaction between the body and the environment needed for perfect execution. The resulting task dynamical systems model the trial-to-trial performance of precision goal-directed actions, such as, for example, the repeated throwing of a ball at a target or the hammering of a nail. Using these models, one can examine how performance arises from the interaction between the geometry of task-specific goal equivalent manifolds, passive sensitivity, control and active stability, and intrinsic noise.

New concepts and methods will be developed for modeling and characterizing trial-to-trial variability in a range of different tasks. The resulting theoretical models will be used to study the mechanisms of variability generation in repeated movements, to determine the simplest model features that are capable of exhibiting observed phenomena, and to examine the dynamical implications of specific control assumptions. The theoretical results will be used to develop new experimental methods and to make experimentally testable qualitative predictions. The resulting conceptual framework and analysis methods will enable researchers to, for the first time, untangle the passive mechanical aspects of movement from the perceptual and neurological aspects believed to be related to active control.

This project involves collaboration between researchers in nonlinear dynamics, movement science (kinesiology), and robotics. In addition to addressing fundamental questions in movement science, our effort will lead to: new noninvasive approaches to studying, monitoring, and diagnosing neurological movement disorders; monitoring progress in physical therapy after surgery or injury; and characterizing motor learning and performance in subjects involved in sports and other precision tasks. In the area of technology, our work will find application in the design of biologically-inspired precision machines and advanced man-machine interfaces needed for such applications as remote

tele-surgery. Such machines will be designed to exploit task redundancy and passive stability properties so that they inherently respond to changes in their operating environment, or internal changes caused, for example, by component wear. This, in turn, could lead to improved repeatability, reliability and service life, even for entirely open loop devices.

Effective start/end date10/1/069/30/10


  • National Science Foundation: $268,000.00


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