Development and Calibration of Pressure-Temperature-Humidity (PTH) Probes for Distributed Atmospheric Monitoring Using Unmanned Aircraft Systems

Abstract

Small unmanned aircraft systems (UAS) are increasingly being used for meteorology and atmospheric monitoring. The ease of deployment makes distributed sensing of parameters such as barometric pressure, temperature, and relative humidity in the lower atmospheric boundary layer feasible. However, constraints on payload size and weight, and to a lesser extent power, limit the types of sensors that can be deployed. The objective of this work was to develop a miniature pressure-temperature-humidity (PTH) probe for UAS integration. A set of eight PTH probes were fabricated and calibrated/validated using an environmental chamber. An automated routine was developed to facilitate calibration and validation from a large set of temperature and relative humidity setpoints. Linear regression was used to apply temperature and relative humidity calibrations. Barometric pressure was calibrated using a 1-point method consisting of an offset. The resulting PTH probes were less than 4 g in mass and consumed less than 1 mA when operated from a 5 VDC source. Measurements were transmitted as a formatted string in ASCII format at 1 Hz over a 3.3 V TTL UART. Prior to calibration, measurements between individual PTH probes were significantly different. After calibration, no significant differences in temperature measurements across all PTH probes were observed, and the level of significance between PTH probes was reduced. Actual differences between calibrated PTH probes were likely to be negligible for most UAS-based applications, regardless of significance. RMSE across all calibrated PTH probes for the pressure, temperature, and relative humidity was less than 31 Pa, 0.13 °C, and 0.8% RH, respectively. The resulting calibrated PTH probes will improve the ability to quantify small variations in ambient conditions during coordinated multi-UAS flights.

Comprehensive Investigation of Unmanned Aerial Vehicles (UAVs): An In-Depth Analysis of Avionics Systems

“…As an alternative to DHT11, SHT75 [266], representing a digital pin-type humidity sensor with ±1.8% typical relative humidity accuracy, was used in [267] to measure air humidity for the purpose of constructing an intelligent weather station. From a different point of view, SHT40 in [268] participated in the construction of pressure-temperature-humidity probes for distributed atmospheric monitoring via a UAV. Lastly, a relative humidity sensor was employed in [269] as a sub-component from a massive project aimed at monitoring the temperature and humidity in Antarctica.…”

MXene/PPy@PDMS sponge-based flexible pressure sensor for human posture recognition with the assistance of a convolutional neural network in deep learning

“…Conductive polymers have become exciting research materials in sensing, energy storage, electromagnetic shielding, and metal corrosion because of their outstanding properties 35 , 36 . Common conductive polymers include polypyrrole (PPy) 37 , polythiophene (PTH) 38 , and polyaniline (PANi) 39 . Among them, PPy has remarkably good conducting properties.…”