Towards the improvement of postural stability through audio bio-feedback

We describe a bio-feedback system for rehabilitation based on an accelerometric sensor, a processing unit and an output unit. The sensory unit, which incorporates a cell with three uni-axial accelerometers and three rate gyroscopes, is mounted on the subject´s back (L5 level) using a velcro belt and allows to evaluate the trunk accelerations in the anterior-posterior (AP) and medial-lateral (ML) directions. The processing unit is composed by a laptop with Arduino board, able to acquire in real time data coming from sensory unit through the data acquisition module of Max/MSP, and to produce an audio output. The output unit is a pair of headphones which produce a kind of sound whose activation level is proportional to the magnitude of patient´s displacement. A set of experiments have been carried out in order to measure the performance of this system, and results show that it can significantly improve rehabilitation times.