Powerline perching with a fixed-wing UAV

Abstract

Small and micro UAVs have enabled a number of new mission capabilities, including navigating in and around buildings and performing perch-and-stare surveillance. However, one of the primary limitations of these small vehicles is endurance, simply because they cannot carry sufficient power for long missions. Recent advances in fixed-wing perching have made it possible to consider a new solution to this problem - landing on a powerline to recharge. Furthermore, because a current carrying conductor generates a magnetic field, a unique opportunity exists to use the powerline not just for recharging, but for localization as well. In this thesis, we seek to develop technologies that will enable a fixed-wing aircraft to land on a powerline using only the powerline's magnetic field and an inertial measurement unit for localization. To achieve this goal, an experimental set-up and preliminary sensing hardware are developed to detect the magnetic field at least 4 meters from the wire. Then, the necessary signal processing and state estimation algorithms are applied to achieve successful localization and overcome problematic field ambiguities. Following this, an onboard sensing system is developed and the high speed tracking of a perching trajectory is demonstrated experimentally. Finally, the position error associated with the aircraft tracking algorithm is analyzed carefully and assessed to be suitable for achieving closed loop perching. The work culminates in a light weight, 30 gram, on-board sensor system with the capability of estimating the position of a perching aircraft in real time at update rates up to 320 Hz, positional accuracies ranging from 2 to 20 centimeters, and delays of about 17 Ms.