Laboratory Evaluation of an Electro-Pneumatic Sampling Method for Real-Time Soil Sensing
2006
Yildirim, S. | Birrell, S.J. | Hummel, J.W.
An automated electro-pneumatic soil sampling method based on pressurized air for real-time soil analysis was developed and tested under laboratory conditions. Pressurized air was applied for 36 ms across a 2.5 cm diameter cylinder to cut a sample from a soil column and convey the sample along a delivery pipe into a container. An electro-pneumatic regulator valve was used to regulate the air pressure at 550, 690, and 830 kPa (80, 100, and 120 psi) using an analog electrical signal. A two-position solenoid valve controlled by a stand-alone microprocessor was used to control pulse duration. Laboratory tests were conducted to determine the effectiveness of positive high-pressure air as a cutting force for different soil conditions. The effects of air pressure level, soil moisture content, soil compaction, and soil type on the quantity of soil sample obtained were investigated. Moisture content and air pressure level were the most significant factors, while compaction was not significant (alpha = 0.05) in terms of mass of soil obtained. Laboratory test results proved that pressurized air was effective in cutting and transporting a soil sample in a short time period (36 ms) for all different soils studied in this experiment. The electro-pneumatic method was also capable of obtaining a consistent amount of soil sample with a coefficient of variation of less than 20% for any individual treatments in the experimental design. The electro-pneumatic soil sampling method is a viable candidate as a soil sampling system for on-the-go soil analysis.
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