Docking two multirotors in midair using relative vision measurements
This addresses the need for real-world deployment of modular robots, though it is incremental as it builds on existing sensor fusion and control methods.
The paper tackled the problem of autonomous midair docking for modular multirotor robots by developing a state estimator and control architecture using onboard sensors, achieving successful and repeatable docking with centimeter-level precision.
Modular robots have been rising in popularity for a variety of applications, and autonomous midair docking is a necessary task for real world deployment of these robots. We present a state estimator based on the extended Kalman filter for relative localization of one multirotor with respect to another using only onboard sensors, specifically an inertial measurement unit and a camera-marker pair. Acceleration and angular velocity measurements along with relative pose measurements from a camera on the first multirotor looking at a marker on the second multirotor are used to estimate the relative position and velocity of the first multirotor with respect to the second, and the absolute attitude of the first multirotor. We also present a control architecture to use these onboard state estimates to control the first multirotor at a desired setpoint with respect to the second. The performance of the estimator and control architecture are experimentally validated by successfully and repeatably performing midair docking -- a task that requires relative position precision on the order of a centimeter.