Design, fabrication and evaluation of a mechanical transducer for real time measurement of tilth aggregate sizes

Abstract

Development of real time and continuous sensing systems for soil physical and mechanical properties provides a valuable tool to obtain inexpensive and rapid information of soil current status and future management in the context of precision agriculture.  This study aimed to design, fabricate and evaluate a mechanical transducer to measure aggregate sizes in real time by determining dynamic strain behavior of commercially available spring tines in field experiments.  Dynamic strain was measured with strain gauges mounted on the spring tines and respective circuits.  Signals acquired from strain gauges were received and saved by a data-acquisition system and then analyzed.  The results of field experiment data was correlated to standard sieve data.  The results show that the transducer’s output voltage increases with increasing aggregates mean diameters and estimated liner equation was D=13. 827V-33.536 with a correlation coefficient of R²=0. 93.  Mean weight diameter (MWD) was obtained with putting the average of the output signals in the equation.  Calculated diameter of the mechanical transducer was approximately 25% higher than standard sieve analyses.

Keywords: aggregation, mechanical sieve, mechanical transducer, real time measurement, strain gauge