Michael P. Sama

A Computational Tool for Estimating Off-Target Application Areas in Agricultural Fields

A computational method for estimating off-target application areas based on the machine-controlled section width and the field shape was developed and implemented in software with a graphical user interface written in the MatLab environment. The program, which is called the Field Coverage Analysis Tool (FieldCAT), includes three modules: data import, data preparation, and coverage analysis. Nine field boundaries were evaluated to test the software using controlled section widths from 0.5 to 27 m and various swath orientations. The estimated off-target application area from the widest section width varied from 9% to 24% depending on the shape and size of the field boundary and was reduced to less than 1% with the smallest section width. The simulated results were also compared to actual field data from 25 different fields. The FieldCAT software tool was able to provide reliable quantitative estimates of the off-target application of inputs that would occur because of limited resolution of the machine-controlled section width and the path orientation in different field shapes.

Estimating off-rate pesticide application errors resulting from agricultural sprayer turning movements

Pesticide application is an essential practice on many U.S. crop farms. Off-rate pesticide application errors may result from velocity differential across the spray boom while turning, pressure fluctuations across the spray boom, or changes in boom-to-canopy height due to undulating terrain. The sprayer path co-ordinates and the status (on or off) of each boom control section were recorded using the sprayer control console which provided map-based automatic boom section control. These data were collected for ten fields of varying shapes and sizes located in central Kentucky. In order to estimate potential errors resulting from sprayer turning movements, a method was developed to compare the differences in application areas between spray boom control sections. The area covered by the center boom control section was considered the “target rate area” and the difference in these areas and the areas covered by remaining control sections were compared to estimate application rate errors. The results of this analysis conducted with sprayer application files collected from ten fields, many containing impassable grassed waterways, indicated that a substantial portion of the fields (6.5–23.8%) could have received application in error by more than ±10% of the target rate. Off-rate application errors exceeding ±10% of the target rate for the study fields tended to increase as the average turning angles increased. The implication of this is that producers may be unintentionally applying at off-label rates in fields of varying shapes and sizes where turning movements are required.

Standardized Evaluation of Dynamic GPS Performance

Efforts are currently underway through ISO to develop a new standard for testing and reporting the dynamic performance of Global Navigation Satellite System (GNSS) receivers. This paper describes the current status of that dynamic test standard, describes how GNSS receivers would be tested under the current version of the standard, and offers some example test data. Discussions show that the standard will provide a clearer understanding of receiver performance in dynamic agricultural settings. Example tests have revealed that there are still some shortcomings that will have to be addressed by developers of the standard.

Pneumatic Control of a Variable Orifice Nozzle

A variable-orifice nozzle with droplet optimization was recently developed and introduced for use on agricultural sprayers. The VariTarget (VT) nozzle reacts to changes in the system flow rate via a metering assembly that is controlled by a diaphragm and spring. As the liquid pressure changes, the VT metering assembly attempts to control the flow rate and spray pattern exiting the nozzle. The goal of this study was to replace the spring controlled “reactive” system with a pneumatically controlled metering assembly. The proposed system would allow for the metering assembly to adjust the flow rate and spray pattern exiting the nozzle by increasing or decreasing air pressure on the diaphragm. Controlled with an electronic regulating valve, the diaphragm air pressure was tested to determine if desired flow rate variation could be achieved. Initial results indicated that increasing air pressure on the diaphragm results in a decreased flow rate through the nozzle as the input carrier pressure remained constant. The VT nozzle discharge rates for the four set carrier pressures (10, 20, 30, and 40 psi) ranged from as low as 0.2 gpm (maximum air pressure at 10 psi carrier pressure) up to 1.8 gpm (minimum air pressure at 40 psi carrier pressure). Based on these data the proposed pneumatic control system has the potential to provide a new method for variable-rate pesticide application where nozzle flow rates and spray patterns can be controlled pneumatically using sprayer system operating values and electronic regulating valves.

Laboratory Performance of a Mass Flow Sensor for Dry Edible Bean Harvesters

Due to the importance of yield monitoring, researchers have been developing systems for crops such as tomatoes, forage, sugar cane, citrus, and coffee. A yield monitoring system for pull type dry edible beans harvester has not yet been developed. The goal of this project was to design and test a drive torque measurement device on a clean grain bucket elevator of a dry bean harvester, and evaluate its potential to be used as a mass flow sensor. Tests were conducted in the Yield Monitor Test Facility (YMTF) of University of Kentucky following the recommendation of ASABE Standard S578 (2007) The device was tested within the flow rate range of 0 to 3.4 kg/s. The largest flow rate errors were ±4.2% at 3.3 kg/s and ±4% at 1.6 kg/s. The average accumulated mass errors of the sensor were less than 3.1% and the maximum accumulated error was 4.9% at a flow rate of 1.8 kg/s.

Development and Preliminary Evaluation of a Spray Deposition Sensing System for Improving Pesticide Application

An electronic, resistance-based sensor array and data acquisition system was developed to measure spray deposition from hydraulic nozzles. The sensor surface consisted of several parallel tin plated copper traces of varying widths with varying gap widths. The system contained an embedded microprocessor to monitor output voltage corresponding to spray deposition every second. In addition, a wireless module was used to transmit the voltage values to a remote laptop. Tests were conducted in two stages to evaluate the performance of the sensor array in an attempt to quantify the spray deposition. Initial tests utilized manual droplet placement on the sensor surface to determine the effects of temperature and droplet size on voltage output. Secondary testing utilized a spray chamber to pass nozzles at different speeds above the sensor surface to determine if output varied based on different application rates or spray droplet classification. Results from this preliminary analysis indicated that manual droplets of 5 and 10 μL resulted in significantly different values from the sensors while temperature did not consistently affect output. Spray chamber test results indicated that different application rates and droplet sizes could be determined using the sensor array.

Specific conductivity sensor performance: II. Field evaluation

The US Environmental Protection Agency (USEPA) has issued guidance on the specific conductivity (EC25°C) of waters discharged from mined lands in the Appalachian Coal Belt Region of the USA. In this guidance, the USEPA states that these waters should have an EC25°C less than 300–500 μS cm−1. Such a requirement places great importance on accurately determining EC25°C. Building upon a laboratory-based evaluation of four types of commercially available continuous logging conductivity sensors, this study examined sensor performance in the more harsh and variable field environments at forested and mined land streams in eastern Kentucky. The objectives of this study were to calculate the white noise variance associated with each sensor type and to evaluate white noise variance in relation to variations in EC25°C and discharge. Results of the study indicate that predominant increases in EC25°C, and to some extent increases in discharge, explain between 35 and 65% of the white noise variance.

Dynamic GNSS Testing and Applications

Satellite-based global navigation systems are a ubiquitous component in modern guidance systems. Automated guidance in agricultural vehicles is a prime example of how Global Navigation Satellite System (GNSS) receivers can be applied to operations requiring a level or precision, or consistency, which may otherwise be unobtainable. This paper discusses efforts at the University of Kentucky to adopt as well as promote the integration of the ISO/WD 12188-1 standard on dynamic testing of satellite based positioning devices used in agriculture with a focus on how data are acquired and processed. A procedure for data acquisition and analysis has been documented to show the uses as well as some of the difficulties involved with testing GNSS devices. Initial results are encouraging for the use of a Tracking Total Station (TTS) as a non-satellite reference given proper application and calibration methods.

Calibration Drift Assessment and Upgrades to the Fan Assessment Numeration System (FANS)

Aerial emissions from animal feeding operations have been a growing concern for rural residents in the U.S. In order to accurately quantify emissions from a livestock facility, the ventilation rates of each fan operating at a facility are needed. One means of providing this information is to create an in-situ calibration for each fan. The original Fans Assessment Numeration System (FANS) was developed for this purpose. Since the first generation FANS units were released major improvements have been made to improve their efficiency and reliability. The purpose of this paper is to outline the new enhancements made to the fourth generation (G4) FANS units and compare the performance of the fourth generation to its predecessors. The most recent updates included a faster travel rate, sealed limit switches, and an adjustable chain tensioning mechanism. In addition to the hardware updates on each of the new units, the FANS software was updated to include Bluetooth wireless connection capabilities, real-time anemometer RPM and estimated ventilation rate readouts. Four newly manufactured G4 FANS units were calibrated and compared to previous generations of the FANS units. A calibration drift assessment was also performed on select individual FANS units over a ten-year period, which found the absolute accuracy of the FANS units do not fluctuate over time unless there are mechanical malfunctions occurring within the FANS device.

Visualizing Airflow Using the Fan Assessment Numeration System (FANS)

A filtering and interpolation technique was investigated for generating 2-D contour plots from raw Fan Assessment Numeration System (FANS) data. Airflow data was acquired at average static pressures varying from 4.4 Pa to 51.7 Pa. High frequency noise was removed using a digital low-pass filter prior to interpolation using a bi-cubic method. The cutoff frequency of the low-pass filter was shown to have a large effect on the amount of noise present in the 2-D contour plot as well as how well trends were preserved. A cutoff frequency of 0.1 Hz was determined to be adequate removing enough system noise without distorting the underlying process. The shape of the airflow distribution was consistent throughout all static pressure tests and could simply be scaled to compensate for static pressure.