Development of soft actuators using a hydrogen-absorbing alloy as a small pressure source

Abstract

The equilibrium plateau pressure of hydrogen-absorbing alloys changes depending on the temperature. Metal hydride actuator applies this pressure difference upon heating as a pressure source to drive the actuator. This characteristic of the hydrogen-absorbing alloys allows the actuator to drive without electricity if a heat source is available. In addition, there is neither driving noise or vibration because the driving force is based on a chemical reaction. Furthermore, hydrogen-absorbing alloys are capable of desorbing (absorbing) hydrogen gas approximately 1000 times of their own volume upon heating, which offer good power-to-weight ratios. Thus, metal hydride actuator has a potential to realize user-friendly characteristics in daily life space, which is difficult to achieve with other types of actuators. We introduce our previous research on metal hydride actuator in this paper. First, we overview the properties of hydrogen-absorbing alloys, and their effective use as a pressure source of metal hydride actuator. Then, we describe application of soft, and flexible structure as an end effector of metal hydride actuator. Finally, our latest research on jack-up tool as a rescue device is summarized as an example of development of soft metal hydride actuator.