EMG-driven shared human-robot compliant control for in-hand object manipulation in hand prostheses.

Objective. The limited functionality of hand prostheses remains one of the main reasons behind the lack of its wide adoption by amputees. Indeed, while commercial prostheses can perform a reasonable number of grasps, they are often inadequate for manipulating the object once in hand. This lack of dexterity drastically restricts the utility of prosthetic hands. We aim at investigating a novel shared control strategy that combines autonomous control of forces exerted by a robotic hand with electromyographic (EMG) decoding to perform robust in-hand object manipulation.Approach. We conduct a three-day long longitudinal study with eight healthy subjects controlling a 16-degrees-of-freedom robotic hand to insert objects in boxes of various orientations. EMG decoding from forearm muscles enables subjects to move, proportionally and simultaneously, the fingers of the robotic hand. The desired object rotation is inferred using two EMG electrodes placed on the shoulder that record the activity of muscles responsible for elevation and depression. During the object interaction phase, the autonomous controller stabilizes and rotates the object to achieve the desired pose. In this study, we compare an incremental and a proportional shoulder-decoding method in combination with two state machine interfaces offering different levels of assistance.Main results. Results indicate that robotic assistance reduces the number of failures by41%and, when combined with an incremental shoulder EMG decoding, leads to faster task completion time (median = 16.9 s), compared to other control conditions. Training to use the assistive device is fast. After one session of practice, all subjects managed to achieve tasks with50%less failures.Significance. Shared control approaches that give some authority to an autonomous controller on-board the prosthesis are an alternative to control schemes relying on EMG decoding alone. This may improve the dexterity and versatility of robotic prosthetic hands for people with trans-radial amputation. By delegating control of forces to the prosthesis' on-board control, one speeds up reaction time and improves the precision of force control. Such a shared control mechanism may enable amputees to perform fine insertion tasks solely using their prosthetic hands. This may restore some of the functionality of the disabled arm.

A validation study of a virtual-based haptic system for endoscopic sinus surgery training.

BACKGROUND: The development of endoscopic sinus surgery (ESS) training simulators for clinical environment applications has reduced the existing shortcomings in conventional teaching methods, creating a standard environment for trainers and trainees in a more accurate and repeatable fashion. MATERIALS AND METHODS: In this research, the validation study of an ESS training simulator has been addressed. It is important to consider components that guide trainees to improve their hand movements control in the orbital floor removal in an ESS operation. Therefore, we defined three tasks to perform: pre-experiment learning, training, and evaluation. In these tasks, the critical regions introduced in the virtual training environment are forbidden to be touched. Recruiting 20 participants, divided into two groups, we investigated the performance metrics: quality (the percentage of the realism for the generated force for orbital floor removal and the usefulness of the proposed training system for the surgical educational curricula.), efficiency (time, path length), and safety (touching the goal and forbidden wall). RESULTS: All recruited participants answered a post-evaluation questionnaire regarding their perceptions of training system realism, potential educational benefits, and practiced skills. We investigate the differences between groups' performance metrics by utilizing the analysis of variance-Kruskal-Wallis test. Acquired results indicate that training before the actual process of the surgery has a significant effect on the accuracy and validity of the process for surgeons. CONCLUSIONS: Utilizing a standardized environment, trainers and trainees are able to carry out a process with regular features. In addition to traditional education methods, trainees can learn the risk of surgical operations. The training simulators can, also, provide a standard method for assessing the skills of surgical and medical students.