Small robots could get more lift when they hover by moving their wings in a 鈥渢reading water鈥� motion instead of flapping them like hovering insects do.
In an experiment with a robotic wing, at the University of Southampton in the UK and at the Swiss Federal Institute of Technology in Lausanne found that flying micro-robots could hover up to 50 per cent more efficiently if they used a wing motion not seen in the natural world.
The researchers studied a flat rectangular wing about 10 centimetres long that was attached to a shoulder-joint similar to what a flying robot might have. They immersed it in a mixture of water, glycerine and fluorescent dye particles and then illuminated this set-up with green light.
Advertisement
Krishna says that the water-glycerine mixture flowed and swirled around the wing in the same way that air would around the much smaller wing of a micro-robot, replicating the interplay of air density and viscosity, among other factors, at the smaller scale. The glow of the dye particles allowed the researchers to measure velocities of fluid flow and visualise vortices, or small whirlpools, that develop under the wing and give it lift.
When they changed the motion of the wing from an insect-inspired flapping to a motion like treading water 鈥� in which the wing tip made a figure eight instead of moving up and down 鈥� the wing took better advantage of these vortices. When doing the treading motion, the vortex stayed close to the wing for longer and pushed it higher, Krishna says.
鈥淚nsects have different muscular and skeletal configurations based on biological need that may prevent them from doing this sort of treading motion,鈥� she says. 鈥淏ut the robotic mechanisms that we have built are capable of doing this.鈥�
鈥淐opying animals is not always optimal,鈥� says at Cornell University in Ithaca, New York. He says that engineers may choose to imitate the physics of animal motion but can also transform those principles in a way that is most useful.
Reference:
