Emulating avian orographic soaring with a small autonomous glider.

Area of Science:

• Aerospace Engineering
• Robotics
• Environmental Science

Background:

• Autonomous flight research often focuses on large thermals and ridges.
• Urban environments present unique challenges for unpowered flight due to localized, turbulent updrafts.

Purpose of the Study:

• To explore autonomous height gain for fixed-wing micro air vehicles (MAVs) in urban orographic updrafts.
• To develop and test a wind-hovering technique for sustained flight in small, turbulent updrafts.

Main Methods:

• Developed a six-degree-of-freedom MAV model using wind-tunnel tests and vortex-lattice calculations.
• Created a cascaded control system for trajectory control within updrafts.
• Analyzed wind fields around buildings and hills, developing an onboard trajectory calculation method.

Main Results:

• Simulations demonstrated successful system behavior in smooth and turbulent flows.
• Flight tests at a hill were consistently successful.
• Flights near a building were limited to ~20 seconds due to wind unsteadiness.

Conclusions:

• The wind-hovering technique is effective for autonomous height gain in stable updrafts, as shown by hill tests.
• Sustained operation near buildings is challenging due to wind gustiness causing updraft loss.
• Further research is needed to adapt the technique for more dynamic urban wind conditions.