A Closed-loop Platform for the Embodiment of Supernumerary Robotic Limbs During Augmented Tasks

Despite the growing interest and the advances in human movement augmentation, i.e., the use of supernumerary robotic limbs (SRLs) to enhance human abilities beyond natural skills, little has been investigated concerning their embodiment. However, embodiment, defined as the sense of ownership and agency over SRLs, is particularly interesting because it has the potential to significantly improve their control performance and modify how the user perceives the human-machine ensemble.In this study, we capitalized on the ability of the closed sensorimotor loop to promote the inclusion of the SRL into the representation of the user's body (i.e., leading to SRL embodiment). We developed and tested a closed-loop platform that allows participants to control a supernumerary robotic arm and simultaneously receive supplementary feedback through vibrotactile stimulation while performing a trimanual task in augmented reality. After interacting with the SRL within the closed-loop platform for approximately 40 minutes, we implicitly evaluated the SRL embodiment by estimating the peripersonal space via a multisensory reaction time task. Preliminary results obtained by five healthy participants suggest that the platform can successfully induce the embodiment of the SRL as testified by the extension of participants' peripersonal space.