A soft metal hydride actuator using LaNi5 alloy and a laminate film bellows

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 actuators, we designed a soft metal hydride (MH) actuator using a copper-coated LaNi₅ alloy and a laminate film bellows. For the purpose of this study, we selected a suitable LaNi₅ alloy and developed a soft and light end-effector for the soft MH actuator. As a result of experimental tests, the LaNi₅ alloy that has a low plateau pressure at room temperature performs well for the MH actuator. Moreover, the end-effector applied to the soft bellows made of an aluminum laminate film is 20 times lighter and 30 times longer than the metal bellows used in a conventional MH actuator. These findings support the efficacy of the soft MH actuator using the LaNi₅ alloy with low plateau pressure and laminate film bellows for the purpose of developing a portable rehabilitation system or a wearable force feedback device in virtual reality.