Abstract: Ionic Polymer Metal Composite (IPMC) is a novel electrically actuated intelligent material with the advantages of big bending dis-placement, low driving voltage, flexible and so on. It has been recognized as one of the most attractive actuators with prospective applications for underwater robots and bionic organs. In this work, a capsule-like robot was introduced with the pectoral and caudal fins made of IPMC. By analyzing the properties of displacement response to square waves with different frequencies and low level voltages, it was found that performance of IPMC are frequency sensitive. Besides, when the absolute value of low level voltage decreases, IPMC could swing on one side with the decrease in amplitudes, whereas the amplitude at high level voltage fluctuates within small ranges at low frequencies.  IPMC tip can approximately maintain when the frequency of driving signal around 30 Hz. Such properties were employed to control the locomotion of robot combining the motions of pectoral and caudal fin. Thus, the locomotions of swimming forward, turning and positioning were realized.

Key words: underwater robot, open-loop control, IPMC, swing property, displacement response ,