Design and calibration of an innovative ultrasonic, arduino based anemometer

A precise estimation of wind intensity and direction is important for many applications. Authors, thanks to a consolidated experience in marine robotics, are building a sail propelled marine drone for a sustainable monitoring of wide sea areas. In particular, sail propulsion assures a near to infinite autonomy since limited energy demand of on board electronic can be assured by renewable sources such as solar cells. However, to correctly manage a sail system, a correct estimation of wind intensity and its direction is essential. Conventional anemometers make use of delicate mechanical moving parts, are therefore not suitable to work autonomously in difficult environments such as the marine one. Commercial ultrasonic anemometers represent a valid alternative but their cost, weight and size need to be optimized for the proposed application which is a cheap, light and relatively small drone. In this work the authors redesigned both acoustic and electronic system to meet the required specifications. Innovations have been suggested in terms of materials, components and introducing a smart measurement algorithm that allowed the authors to simplify the design, construction and calibration of the instrument. Finally, the system has been tested and calibrated in a wind tunnel, introducing a simple and effective calibration algorithm able to drastically reject disturbances arising from interference between mechanical system and the wind flow under measurement.