Miniature multihole airflow sensor for lightweight aircraft over wide speed and angular range

TL;DR

This paper introduces a lightweight, robust multihole airflow sensor suitable for small UAVs, capable of accurately measuring airspeed and angles of attack at low speeds near stall conditions.

Contribution

The study presents a novel, integrated multihole pressure probe design, optimized for lightweight UAVs, with comprehensive wind tunnel testing and outdoor validation.

Findings

Achieved mean absolute errors of 0.44 m/s for airspeed and 0.16° for angles.

Validated sensor performance during acrobatic maneuvers near stall.

Sensor weight reduced to 9 grams, suitable for small UAVs.

Abstract

An aircraft's airspeed, angle of attack, and angle of side slip are crucial to its safety, especially when flying close to the stall regime. Various solutions exist, including pitot tubes, angular vanes, and multihole pressure probes. However, current sensors are either too heavy (>30 g) or require large airspeeds (>20 m/s), making them unsuitable for small uncrewed aerial vehicles. We propose a novel multihole pressure probe, integrating sensing electronics in a single-component structure, resulting in a mechanically robust and lightweight sensor (9 g), which we released to the public domain. Since there is no consensus on two critical design parameters, tip shape (conical vs spherical) and hole spacing (distance between holes), we provide a study on measurement accuracy and noise generation using wind tunnel experiments. The sensor is calibrated using a multivariate polynomial regression model over an airspeed range of 3-27 m/s and an angle of attack/sideslip range of +-35{\deg}, achieving a mean absolute error of 0.44 m/s and 0.16{\deg}. Finally, we validated the sensor in outdoor flights near the stall regime. Our probe enabled accurate estimations of airspeed, angle of attack and sideslip during different acrobatic manoeuvres. Due to its size and weight, this sensor will enable safe flight for lightweight, uncrewed aerial vehicles flying at low speeds close to the stall regime.