Researchers from EPFL, Duke University, and Instituto Superior Tecnico built ZBot, a larval zebrafish-inspired swimming robot 200 times the size of the real fish, to study why intermittent bout-and-glide swimming is more energy efficient than continuous tail-beating. Using a neurocomputational model built around Central Pattern Generators and bout-gate modules, the team replicated multiple zebrafish swimming gaits and tested performance across fluids of varying viscosity. They found intermittent swimming reduces energy consumption at all velocities but caps top speed at about 60% of continuous swimming, and propose a new 'actuator efficiency' hypothesis: bout-glide cycling keeps motors (or muscles) operating in their most efficient load range rather than the drag-reduction explanation alone. The findings suggest underwater robots could switch between energy-saving intermittent gaits for cruising and continuous gaits for high-speed maneuvers.
Questions this post answers
Why is intermittent bout-and-glide swimming more energy efficient than continuous swimming for fish-like robots?
Intermittent swimming keeps actuators operating in their most efficient load range rather than persistently underloaded, since both robotic servomotors and biological muscles follow an inverted U-shaped efficiency curve. Experiments on the zebrafish-inspired robot ZBot showed intermittent swimming reduces energy use at all velocities compared to continuous tail-beating, though top speed drops to about 60% of continuous swimming. Developers building energy-aware control systems can find bioinspired engineering research like this on daily.dev.