When GPS Won't Work for Drones

We noted this in navigating interior spaces, but GPS also has limitations outdoors

Autonomous drones perform search and rescue without the need for GPS

A new drone developed at Massachusetts Institute of Technology (MIT) could be the key to finding hikers lost in the woods. A challenge with search and rescue operations for people lost in forests is that helicopters and drones which fly above the tree canopy cannot see down to the forest floor to locate them, so autonomous drones which can weave between trees are a proposed alternative. However, most autonomous drones rely on GPS signals which can be weak or non-existent in heavily forested areas. Now researchers at MIT have developed a flying drone which does not rely on GPS but uses onboard computation and wireless communication instead. ... "