But a new class of machines are beginning to sense their world more like we do. Boston Dynamics, for instance, makes the famous SpotMini robot dog. This machine doesn’t use lidar because lidar is computationally and energetically expensive. So instead, a handler remote-controls the machine through an environment as cameras capture its surroundings. Armed with this information, the robot can then walk the same route autonomously, using its cameras to eyeball a now-familiar world.

This new drone system works in much the same way. You can’t bolt a bulky lidar on a drone and expect it to get off the ground, so this system also runs on cameras. The researchers trained the drones by, well, holding them and “flying” them through the obstacle course first (comical mouthed airplane noises excluded), like SpotMini first walking a route. This allowed them to collect images, tens of thousands of them. The researchers used all this data to train a neural network on how to fly through the obstacle course, not with a detailed 3-D lidar map, but with sight.

When they let the drone loose, it could navigate autonomously using its onboard camera. “The drone receives an image from the camera and the neural network outputs, Hey drone, now you have to go two meters to the left,” says University of Zurich roboticist Antonio Loquercio, who helped develop the system. The drone is constantly taking in these images, processing them, and correcting its course, all based on its training on the neural network.

Because the drone isn’t just relying on a static map of its environment, it’s better equipped to react to the unexpected. “During data generation, we moved one or two gates on the track and adapted the trajectory,” says roboticist Elia Kaufmann, also of the University of Zurich. In other words, part of the robot’s training was to deal with changes in the environment.

Even when humans throw in challenges like this, the drone managed to complete 50 out of 50 laps without a collision. In fact, it bested a pro pilot the researchers brought in to fly the same course, who managed 45 out of 50, albeit at a greater speed—the human was an average of three times faster than the robot. “Drone pilots fly very, very aggressively,” says Loquercio. “They are more open to take risks, way less conservative than what our current approach is.”