Using an embedded microcontroller system to excite vibrating wire transducers

Abstract

Vibrating wire transducers are spread all throughout a hydroelectric dam internal structure, grubbed in concrete since the build phase. The transducer includes a piano-like wire mechanically stressed in direct proportion to the measured physical quantity (pressure, displacement, force, etc.). Two electrical coils include the wire in the armature gap, being able either to excite mechanical vibrations or to translate them into electrical signals. A high quality factor oscillator can be built using the ensemble in the feedback path, or successive "excitation" and "listening" periods can be used. In both cases, the measured frequency represents the physical quantity. The measuring ends are collected, using long connection cables, in some hard-to-reach internal dedicated rooms. Low weight and size portable measuring devices are needed. One of the most at hand solutions is using microcontroller-based units. The paper analyzes possible ways of excitation signal synthesis for different microcontroller families.