Finding hikers who get lost in the woods can be grueling and dangerous... but drones with AI can make it much faster.

Every year hundreds of thousands of people get lost in the woods worldwide.

This is a good use of artificial intelligence because navigating forests is challenging:

This research is a premiere in the fields of artificial intelligence and robotics and could soon be used in parallel with rescue teams to search for people lost in the wild faster than would be achievable by human rescuers alone.

“While drones flying at high altitudes are already being used commercially (see Amazon or DHL), drones cannot yet fly autonomously in complex environments, such as dense forests. In these environments, any little error may result in a crash, and robots need a powerful brain in order to make sense of the complex world around them.”

So much for Robin Hood and his merry men. 

If Robin Hood were around today he'd be helping find lost people in forests, too.

Rather, it's impossible to live as a noble outlaw when bloodthirsty drones can be used hunt you down and turn you over to evil Prince John.

I see this would have a problem when a trail splits.

As Three Pipe says below, going off trail provides additional challenges. 

Nathaniel, I think you're right in the sense that this control system only focuses on staying on a trail.  It's probably not a huge stretch to plug this into existing traversal algorithms, which know for example how to avoid getting stuck in loops and how to ensure that an entire network of paths are covered. 

When machine learning is added to the drones they'll be more clever in navigating.