Using Robot Skin to Support Physical Therapy Routines with a Lightweight Upper-Limb Exoskeleton

Physical therapy is the pillar of rehabilitation for disabilities caused by neurological disorders, however not every patient has access to it due to the lack of human resources. Robot-based rehabilitation devices such as exoskeletons can contribute to the solution of this challenge by providing benefits such as task-oriented exercise routines. In order to increase the therapy frequency and intensity, we propose the use of robot skin as multi-sensory interface to maximize the wearability and support of a lightweight upper-limb exoskeleton for elbow flexion and extension. The robot skin covered exoskeleton measures acceleration, proximity, and interaction forces, allowing the implementation of different control modes which are inspired by physical therapy such as passive movement, active support, and resistance training. To assess every therapy-inspired control mode, a preliminary study analyzing sEMG recordings of the biceps during exoskeleton use was conducted with four healthy subjects to test the functionality of the exoskeleton. Our results show that higher assistive levels under the supportive therapy control modes result in larger reductions of normalized sEMG (>40% in passive exercises), whereas higher resistive levels result in an increase of normalized sEMG (>30% in resistive exercises). Thus, enabling the exoskeleton to use multi-sensory interfaces to implement therapy support routines.