HERMIT: A Robotic Hand Mirror Therapy Device, Utilizing a Spiral CAM Linkage for Children with Cerebral Palsy

Children with hemiplegic cerebral palsy (CP) often have limited hand function, hindering their ability to perform daily activities. Although constraint-induced therapy and hand-arm bimanual intensive training have shown clinical efficacy, they are intensive and may not be suitable for children who are more severely impaired. Mirror therapy, on the other hand, may be a more feasible option, but typically leaves the affected hand inactive, limiting sensory feedback, a crucial component in motor control and learning. Robotics can enhance mirror therapy by allowing the movement of the unaffected hand to control a robotic device on the affected hand, thus providing necessary sensory feedback. However, robotic mirror therapy has primarily been studied in adult stroke patients, and its efficacy in children with CP has not been rigorously evaluated. Moreover, most developed devices are unilateral and focus on proximal joints rather than the hand. To address this challenge, we present the preliminary design of a hand end-effector robot for mirror therapy (HERMIT) in children with CP. Each side of the robot features a novel spiral cam linkage mechanism. Additionally, the measured movement on one side of the robot, detected via a sensor, controls the movement on the other side, which is driven by a motor. Furthermore, HERMIT enables the user to attach their fingers and thumb from the palmar side. HERMIT also sits on a sliding aluminum frame, allowing for adjustability depending on should-width. Future studies aim to validate the effectiveness of robotic mirror therapy in children with CP.