Robots can use their own whirring to echolocate and avoid collisions

The whirring, squeaking or clicking created by robots' wheels, joints and motors are usually undesirable, and engineers work hard to minimise them. But a research team has found that they can be useful as part of an echolocation system to aid navigation and avoid crashes. Most robots, whether they walk, roll or fly create some sort of background noise. Flying drones, in particular, are extremely noisy.