Characteristics of Temperature–Pressure of Metal-Hydride Actuation System Using Hydrogen Pressure Change

This paper is an analysis of driving characteristics of a metal-hydrogen (MH) actuator for driving a rehabilitative system using environmentally friendly hydrogen. The temperature–pressure characteristics of the MH actuator according to the temperature control of the Peltier element were analyzed to apply to the driving of the rehabilitative system to assist the daily activities of the patient. In this experiment, Peltier element is used to control the temperature of MH module which contains hydrogen storage alloy with on/off control scheme and fan on/off. To improve the thermal conductivity of the hydrogen-absorbing alloy, an assembly of MH module based on copper has been used. The control currents of the thermoelectric elements were 1 A and 2 A, and the temperature control range was between 35° and 70°. As the result of experiments, it is proper to act fan only while cooling duration and there exist a proper cooling current to drop temperature rapidly. It takes about 100 s to increase to 70 °C and drop to 35 °C of MH module temperature and about 90 s to increase to 70 °C and drop to 40 °C in ambient temperature 30 °C while fan is on only in cooling duration. The desirable characteristics of MH actuator, which makes it suitable for the uses in medical and rehabilitation applications, have been also studied.