Evaluation of performance and heart rate variability during intensive usage of a BCI-controlled hand exoskeleton

Brain-computer interfaces (BCI) in combination with assistive robotic devices, such as wearable robotics, has the potential of augmenting the capabilities of disabled people to carry out activities of daily living with success. To improve applicability of such systems, workload and stress should be reduced to a minimal level. In this paper, the degradation of the performance of EEG hand-exoskeleton control with the exhaustive use of the interfaces is analysed through the monitoring of user's physiological reactions. Eleven BCI-naive volunteers participated in the study. The participants performed several open/close hand motor imagery trials for 6 minutes. After completing the task, both the NASA TLX questionnaire and self-assessment manikin (SAM) were submitted to the user. The results broadly suggest that there are significant differences (p-value<; 0.05) in heart rate variability (HRV) changes between subjects that showed good and poor performance using the BNCI. In addition, these objectives results are corroborate with the results of subject's workload perception and emotional responses assessed through NASA-TLX questionnaires and Self-Assessment Manikin (SAM) respectively. Our main finding is that the subjects' performance using a BCI-controlled hand exoskeleton produce physiological reactions in that subjects.