The brain-machine interface (BMI) or brain-computer interface (BCI) is an interface technology that utilizes neurophysiological signals from the brain to control external machines or computers, and we have developed a BMI-based occupational therapy-assist suit (BOTAS) for paralyzed upper extremities. Sensorimotor rhythm, P300 (Komatsu et al., 2010), steady-state visual evoked potential (SSVEP) (Sakurada et al., 2013) and electromyography (EMG) signals (Kawase et al., 2012, 2013) were used to drive the in-house assist suit for reaching and grasping movements. In this study, we developed a wearable BMI-based exoskeleton for neurorehabilitation and daily actions (BRENDA) for reaching and grasping movements.
The BRENDA had a torque-controlled motor to assist reaching movements with flexion/extension of an elbow and three position-controlled motors to assist grasping/opening movements. The motors were controlled based on signals extracted from EEG and EMG. A LED panel for eliciting SSVEP with 40Hz green/blue flickering stimuli was attached to a hand portion of the BRENDA. Electrodes for EMG measurement were attached to an arm sleeve beneath the BRENDA. An amplifier of the biological signals, batteries and a PC for controlling the whole system were stored in a case, and the user wore the case at the waist.
In an experiment, the BRENDA worn by an able-bodied subject (a 35-year-old female) realized reaching movements with flexion/extension of her elbow, which were triggered by EMG signals, and grasping/opening movements, which were triggered by SSVEP elicited by 40Hz green/blue flickering stimuli.
The new exoskeleton may be useful for practical rehabilitation and support of daily actions based on the users' intention.