Development of an actuation system to apply hydrogen storage alloy for the rehabilitative system

BACKGROUND: Hydrogen has advantages that can be used as energy, but research on safe use is needed. OBJECTIVE: In this study, an actuation system for rehabilitation is developed to drive the actuator using hydrogen storage alloy and to analyze the hydrogen release characteristics of the alloy. METHODS: The system is automatically control and report the pressure, temperature and hydrogen flow using LabVIEW-based modules and LabVIEW software. Zr0.9Ti0.1Cr0.6Fe1.4 alloy was selected as hydrogen storage alloy. 5 MPa of hydrogen pressure was applied at 8.56 g of alloy powder for activation process and the temperature outside was maintained at 19°C to 21°C. The amount of hydrogen absorption was measured about 1.47 wt%. The actuation test was conducted at the temperature from 25°C to 80°C, increased by every 5°C. The actuation height was measured at each load of 5, 10, 15, and 20 kg. The voltage and current which is applied to peltier elements were set to 5.0 V and 2.5 A. The pressure changing in the system was checked for 5 min for each temperature, however, if the temperature at which the pressure inside the system changed, the time to heat the module was increased to 20 min. Hydrogen was first released at 70°C. RESULTS: The loads of 5 and 10 kg were raised by 87 and 19 mm at 70°C, respectively. At 75°C, loads of 5, 10 and 15 kg were raised by 131, 70, and 15 mm, respectively. At 80°C, 5, 10, 15, and 20 kg were raised by 150, the end of the actuator, 83, 55, and 28 mm, respectively. CONCLUSIONS: The actuation system in this paper can be applied to assistive device and rehabilitation system for assisting the movement of daily life of the elderly or people with disability.