Comparison of feed-forward control strategies for simplified vertical hopping model with intrinsic muscle properties.

To analyse walking, running or hopping motions, models with high degrees of freedom are usually used. However simple reductionist models are advantageous within certain limits. In a simple manner, the hopping motion is generally modelled by a spring-mass system, resulting in piecewise smooth dynamics with marginally stable periodic solutions.

Response to perturbation during quiet standing resembles delayed state feedback optimized for performance and robustness.

Postural sway is a result of a complex action-reaction feedback mechanism generated by the interplay between the environment, the sensory perception, the neural system and the musculation. Postural oscillations are complex, possibly even chaotic. Therefore fitting deterministic models on measured time signals is ambiguous.

Rolling balance board of adjustable geometry as a tool to assess balancing skill and to estimate reaction time delay.

The relation between balancing performance and reaction time is investigated for human subjects balancing on rolling balance board of adjustable physical parameters: adjustable rolling radius and adjustable board elevation . A well-defined measure of balancing performance is whether a subject can or cannot balance on balance board with a given geometry (, ). The balancing ability is linked to the stabilizability of the underlying two-degree-of-freedom mechanical model subject to a delayed proportional-derivative feedback control.