REEF Estimator: A Simplified Open Source Estimator and Controller for Multirotors

Researchers working on projects that involve multirotor platforms often spend a disproportionate amount of time and effort on the vehicle infrastructure rather than the intended research. This is especially true for graduate students or research laboratories attempting to establish flight capabilities for the first time and this paper aims to expedite that process. The paper provides a complete commercial-off-the-shelf (COTS) hardware and Robot Operating System (ROS) node-based software solution to support reliable and repeatable flight capability for multirotor systems without the need for Global Positioning System (GPS) or motion capture systems. We detail a simplified filtering approach that breaks the typical multirotor estimator into more accessible pieces; an attitude filter, a velocity filter, and an altitude filter and their associated controllers that take velocity, altitude, and yaw-rate control requests. This solution enables the user to have a stable flight from manual or higher-level guidance inputs while providing a solid baseline implementation of GPS-denied multirotor systems. Links are provided for the open-source algorithms, multirotor simulator, hardware list and assembly instructions.