Development of a Low-Cost Three-Axis Anemometer for Analysis of Various Wind Phenomena

Abstract

Distributed three-axis anemometers are needed for high spatial resolution networks to understand the flow of wind for the study of various phenomena. In order to achieve high spatial coverage, the cost of each three-axis anemometer must be reduced while maintaining accuracy and durability. I achieved a low-cost three-axis anemometer by implementing guided-parallel beam structures and incorporating infrared (IR) sensor technology. The sensor can measure wind speeds over 100 mph with an accuracy under 0:2 mph while costing a fraction of existing commercial anemometer prices. Three parallel beam structures are oriented and designed to decompose the wind force along each axis and eliminate cross-coupling between each axis. The IR sensor pair converts the physical displacement to a voltage to determine the velocity of the wind. The initial prototypes showed the concept to be favorable and led to further design iterations. Through the emergence of 3D printing and in-house printed circuit board (PCB) milling, I transitioned to a faster design-buildtest methodology. This thesis details several of the challenges I encountered during this process. One such challenge was the openly exposed IR phototransistor which caused misreading due to its exposure to external infrared light sources. This challenge was addressed through the profiling of the IR sensors and evaluating methods for mitigating the effects of external interference. The findings of the IR profiling and subsequent research led to the development of a new force transducer to convert the displacement of the parallel suspensions to a force measurement. The force transducer uses principles of total internal reflection and frustrated total internal reflection to measure the amount of force applied to the transducer. The force transducer was fabricated using polydimethylsiloxane (PDMS) as the material for the optical waveguide. The optically-based force transducer performs with similar characteristics as available force sensors and can be implemented into a low-cost three-axis anemometer. The research has led to the development of technology that can be implemented in a variety of situations to measure fluid flow.