title: Virtual grasping: closed-loop force control using electrotactile feedback.
abstract: Closing the control loop by providing somatosensory feedback to the user of a prosthesis is a well-known, long standing challenge in the field of prosthetics. Various approaches have been investigated for feedback restoration, ranging from direct neural stimulation to noninvasive sensory substitution methods. Although there are many studies presenting closed-loop systems, only a few of them objectively evaluated the closed-loop performance, mostly using vibrotactile stimulation. Importantly, the conclusions about the utility of the feedback were partly contradictory. The goal of the current study was to systematically investigate the capability of human subjects to control grasping force in closed loop using electrotactile feedback. We have developed a realistic experimental setup for virtual grasping, which operated in real time, included a set of real life objects, as well as a graphical and dynamical model of the prosthesis. We have used the setup to test 10 healthy, able bodied subjects to investigate the role of training, feedback and feedforward control, robustness of the closed loop, and the ability of the human subjects to generalize the control to previously "unseen" objects. Overall, the outcomes of this study are very optimistic with regard to the benefits of feedback and reveal various, practically relevant, aspects of closed-loop control.
authors: Department for Systems, Signals and Control, Faculty of Technical Sciences, University of Novi Sad, Novi Sad, Serbia.
authors: Nikola
authors: N
authors: Jorgovanovic
authors: Department of Neurorehabilitation Engineering, University Medical Center Göttingen, Georg-August University, Göttingen, Germany.
authors: Strahinja
authors: S
authors: Dosen
authors: Department for Systems, Signals and Control, Faculty of Technical Sciences, University of Novi Sad, Novi Sad, Serbia.
authors: Damir J
authors: DJ
authors: Djozic
authors: Department for Systems, Signals and Control, Faculty of Technical Sciences, University of Novi Sad, Novi Sad, Serbia.
authors: Goran
authors: G
authors: Krajoski
authors: Department of Neurorehabilitation Engineering, University Medical Center Göttingen, Georg-August University, Göttingen, Germany.
authors: Dario
authors: D
authors: Farina
mesh_terms: D000328:Adult; D001186:Artificial Limbs; D003196:Computer Graphics; D003199:Computer Systems; D004558:Electric Stimulation; D005246:Feedback; D005260:Female; D006225:Hand / Q000502:physiology*; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D011187:Posture; D011474:Prosthesis Design; D015203:Reproducibility of Results