This drone uses a buzzer and microphone set-up to navigate by echolocation Frederike Dumbgen et al. arXiv:2301.08327v1
A drone can guide itself and map environments via echolocation using a simple buzzer and microphone set-up, much like how a bat uses sound to see in the dark.
For robots to be able to move autonomously, they need to determine where they are in space and whether any obstacles lie in their path. This is typically done using GPS sensors, cameras or devices that use radio waves or lasers, but these can be too heavy for small robots …
