Analytics for Real-Time Inertial Localization of the Tethered Aircraft Unmanned System

The Tethered Aircraft Unmanned System enables long-term distributed sampling at altitude via an array of sensor suites embedded along the power tether. As the aircraft traverses the location of the sensors along the tether and during operation remains unknown. In this work, we propose an inertial-based method for estimating real-time localization of the sensor array. We have integrated an inertial measurement unit into each sensor suite and the orientation of each sensor is transformed into the world frame using a Madgwick estimator. The power tether is modeled as an asymmetric catenary which enables us to define a subspace of the explorable volume for system initialization and periodic online re-calibrations. The system flew numerous curvilinear trajectories in a laboratory setting. Analysis of the intercomparison between our approach and Vicon ground truth positional data shows average RMSE of 0.524, 0.493, and 0.625 m in the N, E, and D axes after 10 s, respectively.