Research Case
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Research Case — Adaptive Morphing in Birds
Meet LisEagle
LisEagle is an avian-inspired drone designed to use many degrees of freedom in its wings and tail, much like a real bird.
Real birds can adapt the shape of their wings and tail to stay stable in gusty air. LisEagle is interesting because researchers tried to give a drone some of that same adaptability.
Why is LisEagle challenging to control?
LisEagle is not a simple flying machine with only a few controls. It has many moving parts that can change shape during flight.
That creates two big challenges:
- the drone has many degrees of freedom
- the effect of one actuator can depend on what the other actuators are doing
This means the system has coupling effects. A change in one part of the drone can influence roll, yaw, pitch, and stability at the same time.
What did the researchers propose?
The researchers proposed a new control method that uses all of the drone’s degrees of freedom instead of simplifying the drone into a smaller set of easy controls.
Their method was designed to:
- use the full shape-changing ability of the drone
- account for state dependencies
- handle coupling between actuators
- keep the drone stable in a controlled indoor setting
What could LisEagle do?
With this control approach, LisEagle was able to:
- maintain stable flight in turbulent airflow
- use wing and tail shape changes to stay steady
- recover from physical perturbations around roll, yaw, and pitch
- remain airborne even when two control surfaces were blocked midair
That last result is especially important. It shows that the drone could compensate for failures in a way that starts to resemble how birds adapt in changing conditions.
Why does this matter for efficiency?
The work was not only about stability. The researchers also explored energy efficiency.
Using Bayesian Optimization onboard, the drone learned which wing and tail configuration used the least power. This improved energy efficiency by up to 11.5%.
So the project shows that shape-changing flight is not only about control. It can also help a drone fly more efficiently.
Key ideas from LisEagle
- Birds use wing and tail shape changes to remain stable.
- Avian-inspired drones can be given similar flexibility.
- More flexibility creates more control complexity.
- Good controllers must handle coupling and state-dependent behavior.
- Adaptive morphing can improve both stability and energy efficiency.
Why this is an important research case
LisEagle is a strong example of engineering science because it combines:
- observation from nature
- modeling and control design
- testing in realistic flight conditions
- robustness against failure
- efficiency through learning and optimization
This work helps show why birds are such powerful inspirations for future flying machines.
Media Credits
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M1Adaptive morphing of wing and tail for stable, resilient, and energy-efficient flight of avian-inspired drones (Supplementary Video 10)Simon Luis Jeger, Valentin Wüest, Charbel Toumieh & Dario Floreano · npj Robot 2, 8 (2024) · 2024 · CC BY 4.0
