Supernumerary robotic limbs (SL) are devices developed to increase human capability. For this to happen, SLs should assist users with minimal cognitive effort and be controlled both independently and in combination with the user’s natural limbs. Despite the development of many SL, their application is limited by a lack of easy-to-use and intuitive controllers. Integrating somatosensory feedback in the control loop could improve this issue. In particular, providing artificial proprioception, a somatosensory modality important for motor control, could help SL users to integrate the SL into their planning and body schema.
My objective is to find strategies to deliver intuitive and understandable proprioceptive feedback from a SL. To do so, I investigated possible ways of providing artificial proprioceptive feedback using 2degrees of freedom (DoFs) tactile cues delivered through electrical stimulation and vibration. I designed a set of mappings that provide position cues from a virtual arm for each feedback modality. Two studies, one for each modality, were conducted.
In the first study, I observed that the intensity of electrical stimulation affected its perception and comfort. I then found that it was easier to differentiate frequency variations than intensity variations. This study brings new insights into electrical stimulation perception and mapping design, considering comfort is rarely addressed in previous studies.
In the second study, I compared two mappings, task space and joint space, for the feedback and control of a virtual arm. Although I did not observe any effect on the performance, I found that the task space mapping was preferred and better understood than the joint space mapping.
Furthermore, a novel vibration feedback device was designed and tested to deliver 3DoFs position cues. The study showed that it is possible to transmit feedback at the torso and back, a location that few studies have considered. Moreover, this study proposes a novel strategy to provide 3DoFs feedback using vibration alone.