Close-Distance Optical Flow Fusion Using EKF for Multirotor UAV Position Estimation

This paper proposes the use of close-distance optical flow measurements to enhance the Extended Kalman Filter (EKF) position and velocity estimation accuracy of Unmanned Aerial Vehicle (UAV) with the use of existing infrastructure in a GPS-denied environment. The scenario assumed in this project involves a UAV navigating through a mine shaft with a stationary central steel cable that passes through the shaft's center. The UAV has a special design with a hole in the center that allows it to fly up and down while keeping the central cable in its geometric center. The UAV is equipped with a camera facing parallel to the cable at a close and constant distance. Using optical flow algorithms, we can estimate the vertical velocity of the UAV. Using the EKF filter, we aim to integrate these velocity measurements with existing measurements from the Inertial Measurement Unit (IMU), magnetometer, and barometer, to improve the accuracy of the UAV's vertical velocity and height measurements.