Online modulation of assistance in robot aided wrist rehabilitation a pilot study on a subject affected by dystonia

In the last two decades robot training in neuro-motor rehabilitation was mainly focused on shoulder-elbow movements. Few examples of devices for training coordinated movements of the wrist have been designed and clinically tested. Such movements are crucial for recovering motor competence and carrying out many ADLs (activities of daily life). Moreover, most of the implemented therapeutic approaches for robot therapy uses point-to-point reaching movements which tend to emphasize the pathological tendency of patients to break down goal-directed movements into a number of jerky sub-movements. In order to address this issue we used our wrist robot and implemented a control scheme characterized by an adapting assistance delivered to the subject to promote recovery and teach correct motor coordination between flexion/extension and abduction/adduction of wrist movement while tracking a target. The main purpose was to promote the emergence of smoothness in the motor control patterns and maximize the recovery of the normal RoM (range of motion). A preliminary pilot study is illustrated in this work; a pediatric subject affected by muscular dystonia was enrolled in the experiment and he was asked to participate to three therapy sessions on consecutive days. The implementation of a new adaptive, assistive force controller is discussed in details and results are reported comparing the effect of robotic therapy for both dynamic and kinematic changes at the beginning and end of the experiment.