Development of a soft metal hydride actuator using a laminate bellows for rehabilitation systems

Rehabilitation systems and assistive technology devices for people with motor disabilities caused by stroke or the aging process require a human-friendly actuator that is soft, compact, slow, noiseless, and environmentally benign. In order to realize these kinds of kinetic rehabilitation systems, we design a soft metal hydride (MH) actuator using a laminate bellows. For the purpose of this study, we develop the soft and light bellows made of a multilayer laminate film. As a result of experimental tests, this laminate bellows is 20 times lighter and 30 times longer than a metal bellows used in a conventional MH actuator. The soft MH actuator using the laminate bellows has hydrogen impermeability, flex durability and adequate passive compliance for human joints. The MH actuator using the laminate bellows can drive at a slow and safe enough speed for rehabilitation of human limbs. These preliminary findings support the efficacy of the soft MH actuator with the laminate bellows for the purpose of developing a kinetic rehabilitation system or a wearable force feedback device in robotic therapy.