[Paper Review] An Experimental Study of Wind Resistance and Power Consumption in MAVs with a Low-Speed Multi-Fan Wind System

Diana A. Olejnik, Sunyi Wang+5 more|arXiv (Cornell University)|Feb 14, 2022

Biomimetic flight and propulsion mechanisms4 citations

TL;DR

This paper presents an open-source, low-cost, multi-fan wind system for experimental MAV testing, enabling controlled steady and gusty wind conditions. Experiments with a flapping-wing MAV and quadrotor show the flapper requires higher pitch angles and benefits from lift at higher wind speeds, while the CrazyFlie maintains more stable power consumption and faster gust response, highlighting the system’s value for improving MAV wind resilience.

ABSTRACT

This paper discusses a low-cost, open-source and open-hardware design and performance evaluation of a low-speed, multi-fan wind system dedicated to micro air vehicle (MAV) testing. In addition, a set of experiments with a flapping wing MAV and rotorcraft is presented, demonstrating the capabilities of the system and the properties of these different types of drones in response to various types of wind. We performed two sets of experiments where a MAV is flying into the wake of the fan system, gathering data about states, battery voltage and current. Firstly, we focus on steady wind conditions with wind speeds ranging from 0.5 m/s to 3.4 m/s. During the second set of experiments, we introduce wind gusts, by periodically modulating the wind speed from 1.3 m/s to 3.4 m/s with wind gust oscillations of 0.5 Hz, 0.25 Hz and 0.125 Hz. The "Flapper" flapping wing MAV requires much larger pitch angles to counter wind than the "CrazyFlie" quadrotor. This is due to the Flapper's larger wing surface. In forward flight, its wings do provide extra lift, considerably reducing the power consumption. In contrast, the CrazyFlie's power consumption stays more constant for different wind speeds. The experiments with the varying wind show a quicker gust response by the CrazyFlie compared with the Flapper drone, but both their responses could be further improved. We expect that the proposed wind gust system will provide a useful tool to the community to achieve such improvements.

Motivation & Objective

• To develop a low-cost, open-source, and open-hardware multi-fan wind system for indoor MAV testing.
• To evaluate wind resistance and power consumption of flapping-wing and rotorcraft MAVs under controlled steady and gusty wind conditions.
• To provide a scalable, accessible experimental platform for improving MAV flight control in real-world windy environments.
• To compare the aerodynamic and energetic performance of bio-inspired flapping-wing MAVs versus conventional quadrotors under wind disturbances.

Proposed method

• The system uses 135 axial fans arranged in 15 modules, each with an independent AVR-based microcontroller for PWM control and tachometer feedback.
• Wind speed is regulated via individual fan control using a Raspberry Pi, enabling precise modulation for steady and periodic gusts.
• The system generates wind speeds from 0.5 m/s to 3.4 m/s and introduces gusts at 0.125 Hz, 0.25 Hz, and 0.5 Hz by modulating fan speeds in a loop.
• Flight data, including battery voltage, current, and state estimates, are collected from two MAVs: the flapping-wing 'Flapper' and the quadrotor 'CrazyFlie'.
• Experiments are conducted in two phases: steady wind at varying speeds and periodic wind gusts with controlled oscillation frequencies.
• Data analysis includes time-series tracking of pitch angle, position, and power consumption, with cubic smoothing splines used to approximate mean power trends.

Experimental results

Research questions

• RQ1 How do flapping-wing and quadrotor MAVs differ in pitch angle response under steady oncoming wind?
• RQ2 What is the relationship between wind speed and power consumption in flapping-wing versus rotorcraft MAVs?
• RQ3 How do MAVs respond to periodic wind gusts of varying frequencies (0.125 Hz, 0.25 Hz, 0.5 Hz)?
• RQ4 Can the proposed multi-fan wind system effectively simulate realistic wind conditions for MAV testing?
• RQ5 What design limitations affect the stability and control performance of flapping-wing MAVs in high-wind scenarios?

Key findings

• The flapping-wing 'Flapper' requires significantly higher pitch angles than the 'CrazyFlie' to counteract wind, due to its larger wing surface area.
• At wind speeds above 2.7 m/s, the Flapper’s power consumption decreases to a minimum of 12.7 W, indicating beneficial lift generation from its wings.
• The 'CrazyFlie' quadrotor maintains a more constant power consumption of approximately 8.8 W across wind speeds, showing less sensitivity to wind variation.
• The 'CrazyFlie' demonstrates a faster response to wind gusts compared to the 'Flapper', which struggles to maintain position even in steady wind at 3.4 m/s.
• The Flapper’s attitude control system is limited at high pitch angles (>40°), requiring attitude-dependent thrust mapping for stable level flight.
• Both MAVs show room for improvement in gust response, underscoring the need for advanced control algorithms validated on the proposed open-hardware wind system.