Small drones increasingly operate indoors, where GPS is unavailable and the heavier sensors normally used for indoor positioning exceed a micro-drone's weight, size, and power budget. Visible light is a practical alternative, because the spaces a drone operates in are already lit. An ordinary lamp can be modulated to act as a navigation beacon, while the drone carries only a small light sensor to detect it. Prior work by Huang et al. navigates a micro-drone toward a single such beacon, recovering the direction of the light from a ring of photodiodes, but it keeps no record of the light field. It therefore cannot distinguish one beacon from another, nor route around an obstacle that blocks the light.

This thesis gives a weight-, size-, and power-constrained micro-drone the navigation those methods lacked, using only on-board light sensing. We design a fused controller that combines two directions. The first is the bearing toward the beacon, read from a ring of photodiodes. The second is a gradient, which the drone estimates from a map of the light field that it builds as it flies. The sensing runs on a custom light-sensing board that fits well within a micro-drone's payload budget. A signal pipeline on the drone then recovers each beacon from the board's noisy output through a frequency analysis, and reports a confidence measure for each reading. We validate the approach in a Webots simulation and in real flight. The drone reaches modulated beacons forming a predetermined path, and routes around an obstacle, using its stored map of the light field when the obstacle blocks the beacon. ... Read more