Haptic feedback through lower limbs exoskeleton for rehabilitation robotics with virtual reality

• Autor(a) principal: Ostan, Ícaro
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/18/18162/tde-15092021-084047/
• topic: Controle de impedância; Haptic feedback; Impedance control; Presença; Presence; Reabilitação robótica; Realidade virtual; Rehabilitation robotics; Retroalimentação háptica; Virtual reality

Rehabilitation robotics along with virtual reality presents an interesting scenario to improve the physical rehabilitation process. In order to take full advantage of this technology, it is crucial to deliver an immersive experience. To perform this task, visual, auditory and haptic, or, in general, multisensory feedback interfaces are implemented. While the virtual reality equipment provides visual and auditory stimuli, usually a robotic device provides the haptic stimuli. This work describes the design and implementation of a multisensory feedback system for infinite walk inside virtual reality. A lower limbs robotic exoskeleton was adapted to function as a haptic interface device, at the same time it assisted the user to perform a pre-recorded trajectory. A virtual environment was modeled and created in order to distract the user. Motion tracking was implemented in order to ensure embodiment, thus, a greater feeling of presence. Tests with ten healthy subjects were performed in order to assess the user experience and evaluate the current setup. Three controllers were tested: an impedance controller, which only delivered haptic assistance; a cascade admittance-impedance controller that delivered haptic assistance and feedback, helping the user to perform a trajectory but restraining its range; and a transparency controller, which simply followed the user\'s movements. Results showed that the cascade controller could track the reference trajectory with similar accuracy as the impedance controller, at the same time it modulated the trajectory to deliver haptic feedback. Furthermore, most physical side effects reported by the users after the experience were due to the exercise rather the exposure to virtual reality; even though this exposure was relatively short, results suggested that the current virtual reality setup is safe and comfortable for an infinite walking task. Regarding immersion and the feeling of presence, spatial presence was the attribute with best results, whereas the involvement and realism were hampered, mainly due to moments of break-in-presence.