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Uchit Nair - Thesis (Final).pdf (1.67 MB)

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Development of a Laser-Guided Variable-Rate Sprayer with Improved Canopy Estimations for Greenhouse Spray Applications

Nair, Uchit
http://rave.ohiolink.edu/etdc/view?acc_num=osu1598018141311507

Abstract Details

2020, Master of Science, Ohio State University, Food, Agricultural and Biological Engineering.
Traditional greenhouse spray technologies are wasteful, with large off-target losses. These chemicals when used in such excessive quantities can be harmful to the environment and create a hazardous work environment for greenhouse workers. The efficiency of the spray system can be improved by using an intelligent variable-rate sprayer. It was able to achieve a reduction in spray volumes by about 45% even with a limited accuracy in its characterization of plant canopies (Yan et al., 2018). The efficiency of the variable-rate system can be improved further by improving its characterization of plant canopies. This was achieved by processing the data obtained from the laser sensor. The processing algorithm (CHBC) developed was a combination of a registration algorithm, clustering algorithm and mirroring. The registration algorithm was used to improve resolution. The clustering algorithm segmented individual plant canopies from the laser data to enable further processing of each canopy separately. Mirroring was used to predict the occluded portions of the plant canopies. CHBC was shown to reduce root mean square error (RMSE) in the canopy width measurements by 46%. It achieved an overall mean RMSE of 25 mm compared to 47 mm recorded by Yan et al. (2018). The sensor height was indirectly proportional to the RMSE recorded by CHBC up to a certain height, after which the RMSE stayed the same. The 'optimal' sensor height for the best performance was calculated based on the limitations of CHBC. The CHBC algorithm was integrated into an existing real-time/inline system developed by Yan et al. (2019) with modifications. The inline operation was converted to an offline operation. A new GUI was designed, and the modifications made to the system were tested in a lab environment to ensure proper function. A convex hull algorithm was also introduced to measure volumes and consequent spray rates for the offline system. The convex hull method was more accurate in measuring volumes, achieving a mean accuracy of 81% compared to 66% when using the Yan et al. (2019) methodology. This improved volume estimation accuracy also resulted in spray savings of 15%. The performance of the offline system was tested in a greenhouse environment by measuring the spray coverage achieved over plant canopies. The offline system managed to significantly reduce spray coverage at the edges of the plant while still maintaining recommended deposition. The coverage at the tops and bottoms of plant canopies with tight row spacing was similar for all systems. The offline system significantly reduced coverage below recommended values at the bottom of canopies with large row spacing. The spray density for these canopies was still sufficient for disease prevention using insecticides and herbicides but not for fungicides. The offline system achieved spray savings of 87% compared to the conventional spray system while also improving the efficiency of the Yan et al. (2019) system by 53%.
Peter Ling, Dr. (Advisor)
Heping Zhu, Dr. (Committee Member)
Ajay Shah, Dr. (Committee Member)
123 p.
Agricultural Engineering; Computer Science
Automation, Clustering, LiDAR, Point Cloud Data Processing, Variable-Rate Spray, Controlled Environment Plant Production, Convex Hull, Offline Operation, Precision Agriculture

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Citations

  • Nair, U. (2020). Development of a Laser-Guided Variable-Rate Sprayer with Improved Canopy Estimations for Greenhouse Spray Applications [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1598018141311507

    APA Style (7th edition)

  • Nair, Uchit. Development of a Laser-Guided Variable-Rate Sprayer with Improved Canopy Estimations for Greenhouse Spray Applications. 2020. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1598018141311507.

    MLA Style (8th edition)

  • Nair, Uchit. "Development of a Laser-Guided Variable-Rate Sprayer with Improved Canopy Estimations for Greenhouse Spray Applications." Master's thesis, Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1598018141311507

    Chicago Manual of Style (17th edition)

osu1598018141311507
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This open access ETD is published by The Ohio State University and OhioLINK.