A PID controller which can help quadcopter hovering.
At present, most search/personal usage quadcopter(drone) uses cheap but low accuracy IMU. However, in this situation, it's really hard for drones to achiever hovering without RC controller. This project is to using additional sensor to help drones hovering automatically.
Cascade PID controller. One is for velocity control, the other one is for movement control.
px4flow optical flow sensor