Design of a low-pressure pneumatically actuated soft-robotic glove to facilitate bilateral training in stroke rehabilitation

Abstract

Stroke is considered the leading cause of long-term disability worldwide. Most stroke survivors will have some degree of paralysis immediately after stroke, which in many could be lost hand motor functions. During the first three months, post-injury, patients often require to undergo repetitive task practice (RTP) therapy to improve coordination, strength, and range of motion in the parietal hand. Many researchers have been exploring the use of soft robotic gloves (SRGs) as portable rehabilitative devices to increase the dosage of RTP. In this thesis, a better design of a pneumatically driven SRG was explored to reduce operating pressure and achieve high flexion forces compared to existing designs of SRGs. The soft actuators were fabricated using silicon with a shore hardness of 10 A. To support the full range of motion of the fingers, actuators were designed to stretch and bend for the four fingers, and an actuator that can stretch, bend, and twist was also designed for the thumb. To facilitate bilateral training, a master-slave control system was developed and integrated in such a way that a movement in the healthy hand actuate similar movement in parietal hand through the SRG. A range of motion (ROM) and blocked tip force (BTF) tests were conducted on the designed soft actuators. All the actuators supported the full ROM of the fingers. An analytical model for the BTF test was developed for the proposed actuators. This was followed by the actual BTF experiment, which revealed that the actuators are capable of creating a BTF of 9.5 N at 99.5 kPa. In addition, the electrical response of the system showed that the actuation speed of the soft actuator is approximately 2 seconds, which is adequate for rehabilitation activities. Finally, the master-slave control system was successful in assisting a healthy subject in performing a pinch, tripod pinch, and a palmar grasp movements.