Synchronizing the tail motion of a robotic fish to a periodic moving source

This study develops a scheme to let a robotic fish synchronize its tail motion to a periodic motion source. First the tail fin and sphere motions are described by two nonlinear oscillators, respectively. The robotic fish equipped with two PVDF pressure sensors, each sensor on one body side is capable to measure the pressure signals from the oscillating sphere. These pressure signals are sent to the synchronization input to the tail oscillator. As two oscillators are synchronized, approximate synchronization with specific phase differences between two motions can be achieved. This control method is expected to be applied to the robotic fish group so they can react properly to periodic inputs from the other fish or from the human body.