Energy-efficient propulsion inspired by whirligig beetles

Whirligig beetle, claimed in the literature to be one of the highest measured for a thrust-generating apparatus within the animal kingdom, has evolved a series of propulsion strategies that may serve as a source of inspiration for designing highly efficient propulsive systems. First, a robotic platform was developed to test an energy-efficient propulsion mechanism inspired by the whirligig beetle. Second, a mathematical model for the robot was proposed to account for the fluid dynamics generated by the robotic swimming. Third, an optimal problem was formulated and solved for the propulsor and beating pattern design. The results indicated that soft middle, stiff end propulsor, and alternating, asymmetrical beating pattern will improve the propulsion efficiency for a swimming robot with four propulsors. Finally, simulation and experiments were conducted to further analyze the effect of beating pattern to the robotic propulsion efficiency. It was found that the oscillated body movement and S-shaped trajectory introduced by the optimal beating pattern would improve the propulsion efficiency for the designed robot.