Location: Application Technology Research2013 Annual Report
1a. Objectives (from AD-416):
To develop two advanced and affordable spray systems that employ intelligent technologies to continuously match system operating parameters to crop characteristics, insect/disease pressures and microclimatic conditions during pesticide applications.
1b. Approach (from AD-416):
Will develop two intelligent expert precision spraying systems implementing five main components to apply the amount of pesticides as needed. The first system will be an air-assisted variable-rate sprayer to be used for shade, flowering and ornamental trees in nurseries. The second system will be a hydraulic boom variable-rate sprayer to be used for flowering container plants in greenhouses and woody ornamentals in nurseries. Due to the similarity of crop structures, the use of the first system can be expanded to other specialty crops such as fruit trees and vineyards, and the second system can be expanded to berries and vegetables. The five components will be: a sensor-controlled unit to control spray outputs that match structures of specific floral and nursery crops, an expert subsystem to assist choosing proper chemicals and application schedules, a direct in-line injection unit to inject concentrated chemicals to individual nozzles to eliminate leftover disposals, a off-target recovery unit to prevent spray off-target losses including drift beyond target areas, and a fluid delivery subsystem to discharge spray outputs with variable rates. All the operations will occur as the sprayer moves past the canopy, providing uniform spray coverage of the canopy with minimum pesticide use and off-target loss beyond the target area. Speciality Crops Research Initiative.
3. Progress Report:
The spray performance of newly developed laser-sensor guided precision sprayer was tested in a laboratory plot, three commercial nursery fields and a vineyard, and was compared with the conventional spray applications. Spray deposition and coverage inside canopies were measured with nylon screens and water sensitive papers to determine the spray quality on target trees. In the laboratory plot, tests were conducted with three travel speeds, two size nozzles and six different tree species of different sizes on the same row. In the first commercial nursery field, tests were conducted with six different sizes of five tree species in two rows and three travel speeds. In the second nursery field, tests were conducted with four similar size trees of the same variety in two rows and three travel speeds to compare spray quality with a constant-rate application. In the third nursery field, tests were conducted in two plots with different widths of multi rows. One plot had four rows of sterling silver linden trees and the other plot had six rows of red oaks. In the vineyard, tests were conducted for the 10 year old red wine grape plants. Spray deposition samples were collected on the trunk, in the front, the middle and in back of three plant canopies and gaps between two plants. Field efficacy tests were conducted to evaluate the control of aphids and powdery mildew with our newly developed air-assisted precision sprayer in four commercial nurseries in Ohio, Oregon and Tennessee. The control efficiency was also compared between the new sprayer and conventional constant-rate sprayers. These tests will be continued for the next three years. System delay times due to the laser-sensor data buffer, software operation, and hydraulic-mechanical component response were determined for a control system used for a LiDAR-guided air-assisted variable-rate sprayer. The delay times were used to determine how far the laser sensor should be mounted ahead of spray nozzles to ensure sufficient time for the sprayer to discharge desired amounts of sprays to the target in real time. A photoelectric detection unit was designed to measure the lag times between when the target was detected by the laser sensor and when the liquid was discharged from the nozzle at various sprayer travel speeds. An algorithm was also developed to compensate the system delay times for the spray outputs to match the detected targets at different travel speeds in real time. A 270° radial range laser scanning sensor was tested for its scanning accuracy to detect tree canopy profiles. Signals from the laser sensor and a ground speed sensor were processed with an embedded computer along with a touch screen mounted on a tractor. An algorithm for data acquisition and 3-Dimensional (3-D) canopy image reconstruction were designed with C++ language and other software. The system accuracy was tested under indoor laboratory conditions with four regular-shape objects and two artificial trees and outdoor conditions with three field trees. Statistical analyses demonstrated the sensor measurements of the objects were not significantly different from those of the actual measurements. The mean RMS errors were not significant for scanning distance of 2 to 5 m and sensor travel speeds of 3.2 to 8.0 km h-1. Both indoor and outdoor tests verified that the wide-range laser sensor had the capability to accurately measure different sizes and shapes of objects. This confirmation offers the potential for the sensor to be integrated into spraying systems and provide variable-rate functions for tree crop applications. This project addresses critical elements for the development of precision sprayer technology envisioned in ARS parent project Objective 1 “Develop precision sprayers that can continuously match canopy characteristics to deliver agrichemicals and bio-products accurately to nursery and fruit crops.