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Precision Agriculture

, Volume 14, Issue 2, pp 215–223 | Cite as

The most common errors of capacitance grain moisture sensors: effect of volume change during harvest

  • M. Csiba
  • A. J. Kovács
  • I. Virág
  • M. Neményi
Article

Abstract

The objective of this study was to investigate the inaccuracy of a capacitance moisture sensor mounted on a combine harvester based on the datasets of six consecutive years. Variation of sensed volume is a major cause of measurement error for a capacitive sensor. The percentage of the sensed volume occupied by grain changes continuously by filling and emptying of the grain bin, which causes a large fluctuation in sensor output during on-the-go moisture sensing. At the beginning of the bin filling process when the grain bin is empty, under-measures were recorded and when it is approximately 60 % full, large over-measures are observed compared to the actual moisture values. This effect mainly influences the precision of the recorded site-specific moisture values and causes inaccurate yield maps. To assess the effect of varying sensed volume content during harvest operation, a bin level transmitter sensor was mounted on the top of the grain bin to continuously measure the height of the grain. A clear correlation between the actual amount of material (available space) in the grain bin to the bias from the standard moisture was demonstrated. The coefficient of determination was R2 = 0.86 for corn (Zea mays L.) and R2 = 0.87 for winter wheat (Triticum aestivum L.). By using equations generated from the datasets of consecutive years (2008, 2009 and 2010), an effective post-correction method for the recorded data is proposed.

Keywords

Capacitance sensing Grain moisture Harvest 

List of symbols

d

Distance (m)

U

Voltage (mV)

s

Grain bin fill (%)

Ch

Grain bin coefficient

ξminn

The highest difference from standard in negative range

ξmaxn

The highest difference from standard in positive range

Notes

Acknowledgments

The research was financed in the framework of the TÁMOP-4.2.2. B-10/1-2010-0018 project entitled “Talentum-Improvements in the conditions available for encouraging talented students at the University of West Hungary” with funds from the European Union and the European Social Fund.

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Copyright information

© Springer Science+Business Media New York 2012

Authors and Affiliations

  • M. Csiba
    • 1
  • A. J. Kovács
    • 1
  • I. Virág
    • 1
  • M. Neményi
    • 1
  1. 1.Faculty of Agricultural and Food SciencesInstitute of Biosystems Engineering, University of West HungaryMosonmagyaróvárHungary

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