A Miniaturized Tadpole Robot Using an Electromagnetic Oscillatory Actuator

In this paper, we propose a miniaturized tadpole-like robot using an electromagnetic oscillatory actuator. The electromagnetic actuator has a simple structure with a moving-magnet type and the body size is 13 mm (length) × 11 mm (height) × 10 mm (width). A tail has the thickness of 100 μm and the length of 20 mm which is twice of the body-length (BL). The tail attached to the oscillatory actuator generates undulatory propulsion for the forward swimming. Moreover, the tadpole robot enables the change of the direction by controlling input signal patterns applied to the oscillatory actuator. Prototypes of the tadpole robot have been manufactured and the thrust force and swimming speed are measured to evaluate the performance of the biomimetic robot in water at various tail-beat frequencies. The maximum thrust force is 42 mN at the tail-beat frequency of 30 Hz with voltage of 3 V, enabling the tadpole robot to swim at the speed of 210 mm·s−1 (6 BL·s−1). The tadpole robot can also change its moving direction with the angular velocity of 21 deg·s−1 at the half pulse pattern of 30 Hz.