Improving Autonomous Soaring via Energy State Estimation and Extremum Seeking Control

This paper introduces autonomous soaring methods that enhance the performance of small autonomous gliders in a thermal soaring environment. Thermal centering control is aided by an asymmetric Savitzky-Golay filter that computes estimates of total energy, rate of change of total energy and the second derivative of total energy using polynomial approximations over a moving time window. Climb rate in the thermal is maximized using extremum seeking control with turn radius as the varying parameter. A simulation environment based on a commercially available multiplayer soaring simulator is described, with low level aircraft control implemented on an Arduino Mega single board computer. Higher level control is implemented on a laptop computer that communicates with the Arduino autopilot over a serial link. The utility of the thermal soaring controller is demonstrated in this high fidelity simulation: stable thermal centering and good convergence to a maximum climb rate is observed, with climb performance of the new controllers exceeding previous methods.