A multi-purpose rehabilitation frame: an apparatus for experimental investigations of human balance and postural...

Moving and rotating platforms are often used in experimental investigations of human balance and postural control. These devices are not well suited for testing elderly and neurologically impaired individuals, because of inherent risk of injury to the experimental subject due to a potential fall. This paper describes a novel mechanical apparatus that generates perturbations to a standing subject by applying pushing forces at the level of the pelvis and can also provide restoring forces in the case of destabilization. The device has two degrees of freedom, which are actuated by hydraulic servo systems, and can deliver a perturbation in any direction comprised within anterio-posterior and medio-lateral postural space. The accuracy and repeatability of the perturbations elicited in eight different directions was evaluated. The results, showing a high degree of correlation between the trajectories in both degrees of freedom of the apparatus, demonstrate that accurate and repeatable perturbations can be imposed on the subjects tested.