Prototype design of a wearable metal hydride actuator using a soft bellows for motor rehabilitation.

A bedside and home rehabilitation system for people with motor disabilities due to stroke or the aging process requires a human-compatible actuator with softness, low noise and a high power-to-weight ratio. To achieve these types of joint motor rehabilitation systems, we designed a wearable metal hydride (MH) actuator using a soft bellows. The purpose of the current study is the development the soft and light bellows made of a polymer laminate film for the MH actuator. As a result of experimental tests, this soft bellows weighs 20 times less and stretches 30 times longer than the metal bellows used in a conventional MH actuator, and it has hydrogen impermeability, flex durability and adequate compliance for human joints. The MH actuator using the soft bellows can drive at a slow and safe enough speed for motor rehabilitation of patients' limbs. These preliminary findings support the efficacy of an MH actuator with a soft bellows for the purpose of developing a system for motor rehabilitation or human power assist.