The evaluation of working speed and depth influence on performance of the tine transducer for measuring tilth aggregate sizes

Abstract

Design, construction and evaluation of a mechanical transducer to measure aggregate sizes in real time were conducted by the same authors.  The spring tines were instrumented using the strain gauges and tested in field conditions.  The main conclusion is that the spring tine transducers could be used as sensors to estimate the mean weight diameter of a given clod size distribution.  In order to evaluate the influence of working speed and depth on performance of the tine transducer, factorial experiments were conducted based on randomized complete block design with three replications.  Working speed and depth were investigated each at three levels.  The results of the variance analysis showed that sensing speed and depth affect tine transducer performance independently.  Sensing speed has a very little impact on performance of tine transducer but sensing depth has a significant impact on performance of tine transducer.  Results also showed that the higher sensing depth and speed the higher horizontal force on the spring tines.  Optimal sensing speed of 5 km h^-1 was chosen in order to reduce the effect of inertia forces due to higher speeds than the critical speed and avoid of plastic deformation and failure of the tine.  Mechanical transducer was calibrated with sensing depth of 70 mm in order to avoid getting into excessive force to the tines and considering the root depth of the various products in the soil.

Keywords: aggregate sizes, sensing speed, sensing depth, mechanical transducer, randomized complete block design, strain gauge