Development of a wearable assistive system for upper-extremity neurorehabilitation

A wearable upper-extremity (UE) exoskeleton robot (RUPERT: Robotic UPper Extremity Repetitive Trainer) targeted for clinical and home-based rehabilitation was jointly developed by Kinetic Muscles Inc. (Tempe, AZ) and Arizona State University. In an effort to keep the mechanical hardware of the robot simple, lightweight and economical, an underactuated design was adopted for the robot's mechanical structure. This underactuated design of the robot which reduces its manipulability, necessitates the demonstration of the feasibility of using the robot for assisted task practice. Thus, the general objective of the dissertation was to develop a control system so that RUPERT can be used as an interactive and cost-effective therapeutic system for assisting functional therapy tasks, despite its simple and underactuated design.The second specific goal of the dissertation was to demonstrate the feasibility of using a hybrid approach to extend the therapeutic utility of RUPERT for assisting real world reach-and-grasp movements. This was achieved by developing a preliminary hybrid system that used RUPERT for assisting arm movements and an electrical stimulation system for assisting hand movements. The system also consisted of an instrumented glove and a balloon like structure that simulates the object used for reach-and-grasp movement practice. Additionally an adaptive controller was developed for modulating the assistance provided to the reaching and grasping components of reach-and-grasp movements. This hybrid system was tested on three stroke subjects for assisting reach-and-grasp movement (both in seated and standing positions). The results from this study not only suggest that a hybrid approach is feasible for reach-and-grasp movement practice with RUPERT, but also that a wearable robot, like RUPERT, can be used for real world task practice by adding one or more simple and inexpensive components into the system.Overall, the work presented in this dissertation acts as stepping stone for the development of a simple, portable, and affordable UE robotic system for real world task-oriented therapy in situations mimicking real-life in both clinical and home environments.The first specific goal of the dissertation was to develop a feedback controller for RUPERT to establish that the robot can be used for the assisted practice of simple therapy tasks, such as reaching movements. This feedback controller supports two adaptive robotic therapy modes that are based on the idea of maximizing active participation from the stroke subject. These two robotic therapy modes were tested on three subjects to evaluate the feasibility of using RUPERT for assisting reaching movements, and also the adaptive capabilities of the two therapy modes. The results from this study indicate that RUPERT can be used for the assisted practice of reaching movements, despite its underactuated design. The two therapy modes were also able to adapt the robot's behavior during therapy based on a subject's motor ability.