Prothesis embodiment : sensory-motor integration of prosthetic devices into the amputee's body image

Abstract

A prosthesis is intended to restore the loss after amputation, this means it should be used not only like a tool, but should also be perceived as part of the body (Prosthesis Embodiment). Good prosthesis embodiment requires that the prosthesis performs harmoniously with the movements of the body. But real prostheses have constructive limitations and their use is not always an optima choice. Therefore an immersive 3D virtual environment was created, in which the subjects, controlling a one DOF virtual hand prosthesis (grasp function only), collected spheres spread within the virtual space. The virtual prosthesis had an ideal behavior or, for comparison, simulated the behavior of the real prosthesis. To close the prosthesis control-loop, a self-made stimulator was developed - the Haptic Brace, which is able to generate complex patterns of multimodal stimulation. The development of Haptic Brace is one important achievement of this thesis, because in comparison with state-of-the-art technologies allows for a more physiological stimulation of the skin. Equipped with such technology, a prosthesis would better reproduce the interaction of the natural limb with the environment, and would allow the amputees to better feel the prosthesis as part of his/her body. Nevertheless, in order to achieve the main goal of this research - Prosthesis Embodiment feedback should be attended by a more intuitive control of the prosthesis. EMG prosthesis control was not the focus of the current work as there-s plenty of research in the field of EMG signal processing. Evaluating the advantages and disadvantages of these methodologies was, however, a serious challenge as there is a lack of available methodology to objectively assess the prosthesis- controllability in all its complexity. Therefore, special attention was dedicated to developing such a methodology, which should be objective and have a general character. This has a crucial importance for future research in the prosthetics field, as, without such an objective measure, it will be hard if not impossible to identify strengths and weaknesses of various approaches, allowing for systematic and real improvements of the prosthesis performance.