Abstract:This paper presents aims at mobility improvement of flexible underwater robots. For this purpose, a novel propulsion method using planar structural vibration pattern is proposed, and tested on two kinds of prototypes. The result of experiments showed the possibility of the movements for multiple directions: forward, backward, turn, rotation, drift, and their combination. These movements are achieved by only one structure with two actuators. The results also indicated the possibility of driving using eigenmodes since movements were concentrated on low driving frequency area. To investigate the relation between movement and structural vibration pattern, we established a simulation model.