Analysis of Induced Muscle Activations by an Affordable, Reconfigurable Robot for Comprehensive Post-Stroke Rehabilitation.

Post-stroke upper-limb impairments affect millions of people worldwide. Low-degree-of-freedom (DoF) end-effector (EE) rehabilitation robots have the potential to provide more affordable and accessible rehabilitation, but there is concern that sacrificing complexity could reduce the efficacy of robotic rehabilitation. In this paper, we present preliminary evidence that a 1-DoF EE rehabilitation robot with multiple configurations can provide comprehensive upper limb exercise. Specifically, we introduce the reconfigurable Rehab CARES system, an expansion of the Haptic TheraDrive robot, and analyze muscle activation data (as measured by surface electromyography, or sEMG) from 11 post-stroke participants performing range of motion (ROM) movements in 3 different robot positions, each of which simulates a different activity of daily living. Our findings indicate that collectively, these positions elicit comprehensive activation of the arm muscles in post-stroke individuals, and that induced motor patterns differ across both positions and levels of user impairment, some of which are likely reflective of compensatory movement strategies. We conclude that with smart reconfiguring, a 1-DoF EE robot is capable of inducing different muscle activation patterns, but does not prevent the user from employing these undesirable compensatory strategies, suggesting that such robots are a promising platform for low-cost rehabilitation exercise and characterizing pathological synergistic movements.