A Mola mola robot

We present a bio-inspired marine robot that emulates the swimming patterns of an ocean sunfish (Mola mola). We test the robot both when it is fixed in place and when it can swim freely. The fins that propel the robot can flap synchronously or asynchronously. By looking at various flapping frequencies and patterns as well as the flow behavior around the fins during these flapping events, we show that there is a linear increase in thrust force by increasing flapping frequency up to the maximum frequency that the robot can achieve. By testing the free-swimming robot and analyzing the movement of its body during its flapping, we show why the synchronous flapping results in larger steady-state swimming speed.