Autonomous Soaring of UAVs using Thermals
Abstract
A thermal is a column of warm rising air caused by differential heating on the ground. Many land birds like vultures and certain hawks use these thermals for long flights without flapping even once. Recent studies have tried using this strategy of thermal soaring for UAVs to improve their range and endurance. Many researchers have successfully flown UAVs autonomously with thermal soaring method. Autonomous thermal soaring includes many challenges like thermal detection, localization of its center, extraction of energy by circling inside the thermal, path planning to encounter maximum number of thermals, etc. The present work explores different strategies available in literature and verify them through detailed simulations. Different methods for modelling thermals are also studied to make the simulations more accurate.
Content
The above figure shows a 6 DOF simulation of an MAV entering, circling and rising inside a thermal
Objectives accomplished till now -
- Extensive literature survey related to thermal soaring for UAVs
- 6 DOF simulation of a glider
- Simulation of netto variometer to detect and measure strength of a thermal
- Implemented algorithms available in literature to estimate and track the center of the thermal
- Implemented algorithms to circle inside a thermal
Future objectives -
- To develop optimal control strategies so that multiple UAVs flying in a field of thermals can cooperatively exploit them to stay aloft for as long as possible
The figure below shows performance of the thermal center tracking algorithm.
The blue data points represent the x-y coordinates of the aircraft as it circles in a thermal
The red data points represent the boundary of the cylindrical thermal
The green data points represent the x-y coordinates of the predicted thermal center
For more details, you can find the copy of my DDP Stage 1 report here.
