Battle the Wind: Improving Flight Stability of a Flapping Wing Micro Air Vehicle Under Wind Disturbance With Onboard Thermistor-Based Airflow Sensing

Abstract

Flyers in nature equip different airflow sensing mechanisms to navigate through wind disturbances with remarkable flight stability. Embracing bio-inspiration, airflow sensing with conventional sensors has long been utilized in flight control for larger micro air vehicles (MAVs). Bio-inspired flapping wing MAVs (FWMAVs) have extremely limited power and payload, therefore implementing onboard airflow sensing has remained a challenge in spite of various attempts at miniaturized airflow sensor designs. This work characterizes the measurement performance of a lightweight off-the-shelf thermistor-based airflow sensor through comparison with a hot-wire probe. Wind tunnel tethered flight tests on a 31.3-gram FWMAV Delfly Nimble examine the onboard sensing performance at low flow speeds (up to 2 m/s), under the influence of flapping motion. This performance characterization further motivates a miniaturized re-design of the airflow sensor with over 40% size and weight reduction. The redesigned airflow sensor helps to realize the first flapping wing MAV free flight with onboard airspeed measurements, providing remarkable flight stability under wind speeds in the range of approximately 0.5 to 1.2 m/s. This embodied sensing configuration pushes the weight and power limit of miniaturized electronics for FWMAVs, providing an easy-to-integrate solution with good performance, and paving the way for more complex control of FWMAVs in dynamic conditions.

Platform Design and Preliminary Test Result of an Insect-like Flapping MAV with Direct Motor-Driven Resonant Wings Utilizing Extension Springs

“…Another approach is to use dual unidirectional DC motors. Each motor is equipped with an independent transmission mechanism on each wing [ 12 , 13 , 14 , 15 ]. In this model, the frequency of each wing can be controlled individually to produce roll motion.…”

Embodied airflow sensing for improved in-gust flight of flapping wing MAVs

“…In nature, flying insects adjust their flight attitude and behaviors by directly sensing the wind with their antennae and body hair, and then acting accordingly ( Fuller et al, 2014 ). Furthermore in the work from ( Wang et al, 2022 ), a more active approach is taken towards FWMAVs flight in wind conditions, thanks to the miniaturization of the airflow sensor which could be integrated onboard directly for free flights. The onboard miniature airflow sensor informs a gain-scheduling control approach in the horizontal position control loop to compensate for forward-facing step-increased wind, blowing on the Delfly Nimble platform.…”