| Summary: | This paper presents the development of a novel low power weigh-in-motion (WIM) system that uses cylindrical piezoelectric (PZT) elements for the dual purpose of sensing axle loads and harvesting mechanical energy for its operation. It provides details on the characterization the PZT sensing elements, the conditioning of their signals and describes the algorithms developed for determining speed, axle load and vehicle classification. These algorithms were coded in MATLAB® and converted to C in a format suitable for installing in a low power microcontroller unit (MCU). The system has the capabilities of monitoring vehicle speed, number of axles, axle spacing, axle loads and vehicle classification. It was tested in the laboratory by applying a range of loads and loading frequencies through a servo-hydraulic loading system. The results suggest sufficient accuracy and precision in measuring vehicle speeds, axle loads and determining vehicle class. Its low power requirements provide an inexpensive and sustainable method for obtaining roadway traffic data.
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