Using a wrist robot for evaluating how human operators learn to perform pointing movements to a rotating frame of reference

An investigation on how humans accomplish pointing movements under predictable rotation of the reference frame was performed. The main purpose of the research was to understand if combined external disturbances in the visual and kinaesthetic feedback may change the strategies used by the CNS (Central Nervous System) to compute motor errors during pointing. Thirteen subjects performed pointing tasks using a 3DOFs wrist mainipulator in a Virtual Reality environment (VR): kinaesthetic and visual perturbations were input by the wrist robot and the VR respectively, in a different combined fashion. Results showed humans strongly increase accuracy in pointing movements when both visual and kinaesthetic synchronized disturbances were applied to wrist robot and virtual reality. Trajectories' plots during the different target sets clearly showed straighter paths; these outcomes were validated and discussed by a kinematic analysis.