Virtual Grasping: Closed-Loop Force Control Using Electrotactile Feedback

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

/ STRU^NI RAD 616.65-006.04-06:616.423-089.894 Pelvic lymphadenectomy for localized prostate cancer

In the era of prostate specific antigen, there is increasing proportion of patients with localized prostate cancer. Accurate preoperative determination of lymph node status is important for adequate selection of treatment option, monitoring of response to treatment and early detection of recurrence. Lymph node invasion (LNI) is crucial prognostic parameter for patients who underwent curative treatment. Despite of continuous improvments of radiological armamentarium, CT, MRI and PET scans are not absolutely reliable in lymph node staging. Many nomograms have been developed for prediction of lymph node status, but accuracy of these statistical models is not better than 78%. Surgery, either open or laparoscopic pelvic lymphadenectmy (PLND), remains a cornerstone in lymph node staging. However, there are several controversies regarding PLND 1) necessity for routine perfoming in each patient, 2) anatomic boundaries for PLND, 3) morbidity of PLND, and 4) diagnostic and therapeutic value. Key words: Surgery, Pelvic lymphadenectomy, ePLND, Aprecise diagnosis of lymph node metastasis status is essential for staging of disease, selection of the appropriate treatment procedure, monitoring of the response to treatment, and early detection of recurrence 1. Therefore lymph node staging seems to be mandatory for patients who are candidates for curative treatment. Clinical preoperative staging is based on radiological procedures or nomograms. Pelvic lymphadenectomy (PLND) is as an essential staging procedure for patients treated with radical prostatectomy (RP) for localized prostate cancer 2. It should provide an adequate specimen for histopathological lymph node evaluation. However, there are several controversial issues regarding PLND: 1) is it necessary to perform PLND in each patient; 2) which anatomical boundaries are required for PLND in high- risk patients; 3) morbidity of PLND 4) diagnostic and therapeutic value of PLND