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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union
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Volume 11, issue 10
Atmos. Meas. Tech., 11, 5519-5530, 2018
https://doi.org/10.5194/amt-11-5519-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Atmos. Meas. Tech., 11, 5519-5530, 2018
https://doi.org/10.5194/amt-11-5519-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 10 Oct 2018

Research article | 10 Oct 2018

Considerations for temperature sensor placement on rotary-wing unmanned aircraft systems

Brian R. Greene1,2,3, Antonio R. Segales2,3,4, Sean Waugh5, Simon Duthoit2,3,4, and Phillip B. Chilson1,2,3 Brian R. Greene et al.
  • 1University of Oklahoma School of Meteorology, Norman, Oklahoma, USA
  • 2Advanced Radar Research Center, University of Oklahoma, Norman, Oklahoma, USA
  • 3Center for Autonomous Sensing and Sampling, University of Oklahoma, Norman, Oklahoma, USA
  • 4University of Oklahoma School of Electrical and Computer Engineering, Norman, Oklahoma, USA
  • 5NOAA/OAR National Severe Storms Laboratory, Norman, Oklahoma, USA

Abstract. Integrating sensors with a rotary-wing unmanned aircraft system (rwUAS) can introduce several sources of biases and uncertainties if not properly accounted for. To maximize the potential for rwUAS to provide reliable observations, it is imperative to have an understanding of their strengths and limitations under varying environmental conditions. This study focuses on the quality of measurements relative to sensor locations on board rwUAS. Typically, thermistors require aspiration and proper siting free of heat sources to make representative measurements of the atmosphere. In an effort to characterize ideal locations for sensor placement, a series of experiments were conducted in the homogeneous environment of an indoor chamber with a pedestal-mounted rwUAS. A suite of thermistors along with a wind probe were mounted inside of a solar shield, which was affixed to a linear actuator arm. The actuator arm was configured such that the sensors within the solar shield would travel underneath the platform into and out of the propeller wash. The actuator arm was displaced horizontally underneath the platform while the motors were throttled to 50%, yielding a time series of temperature and wind speed that could be compared to temperatures being collected in the ambient environment. Results indicate that temperatures may be biased in the order of 0.5–1.0°C and vary appreciably without aspiration, sensors placed close to the tips of the rotors may experience biases due to frictional and compressional heating as a result of turbulent fluctuations, and sensors in proximity to motors may experience biases approaching 1°C. From these trials, it has been determined that sensor placement underneath a propeller on an rwUAS a distance of one quarter the length of the propeller from the tip is most likely to be minimally impacted from influences of turbulence and motor, compressional, and frictional heating while still maintaining adequate airflow. When opting to use rotor wash as a means for sensor aspiration, the user must be cognizant of these potential sources of platform-induced heating when determining sensor location.

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With the recent commercial availability of rotary-wing unmanned aircraft systems (rwUAS), their ability to collect observations in the lower atmosphere is quickly being realized. However, integrating sensors with an rwUAS can introduce errors if not sited properly. This study discusses an objective method of determining some of these error sources in temperature, including improper airflow and rotary motor heating. Errors can be mitigated by mounting thermistors under propellers near the tips.
With the recent commercial availability of rotary-wing unmanned aircraft systems (rwUAS), their...
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