Design, Development and Preliminary Testing of a Passive Upper Extremity ExoNET in Post Stroke

Robot assistive devices and wearable exoskeletons are increasingly being employed as they showed to have great potential and are returning prominent results in post-stroke rehabilitation therapies. Among these, passive devices can support patients to initiate movements themselves and encourage active training at the same time. Here we investigate the abilities of an ExoNET robot composed of diagonal spring elements, configured to provide gravity compensation. We first present the development and testing of the device, and further test its ability to enhance therapy by providing anti-gravity torques to the patient’s joints. The resulting device is safe, light-weight, non-intimidating, and inexpensive. In addition, the ExoNET incorporated a novel shoulder mechanism that allows for all three degrees of freedom of the shoulder joint. This was tested on healthy young individuals in our lab, and then tested on an individual who previously had a stroke, in five therapy sessions where we collected kinematic and electromyography data. Here we present the preliminary analysis of range of motion across days of practice. In particular, we developed a coverage algorithm that uses statistical distributions to gauge a person’s range of motion. We found that the coverage of healthy and paretic wrist positions decreased after donning the ExoNET, which might be caused by the encumbrance that the device introduce. The ExoNET also reduced the coverage of velocities. Interestingly, by the end of 45 minutes of therapy while wearing the ExoNET, the coverage of velocity but not position increased.