Development and test of an autonomous air-assisted sprayer based on single hanging track for solar greenhouse

Abstract

Manual spray operations of conventional pesticides in the greenhouse are highly dependent on labor and have been associated with potential health risks. To overcome the constraints the narrow crop space and the complexity of auxiliary facilities impose on ground autonomous sprayers, this study developed an autonomous air-assisted sprayer based on a single hanging track for solar greenhouses. The spray distribution from the boom and spray patterns were evaluated. Laboratory tests were conducted to investigate the airflow distribution and static spray distribution of the boom. The sprayer was tested on cucumber crops in a solar greenhouse to evaluate the performances of two spray patterns: spraying during boom rising-traveling (P1) and during traveling-falling (P2). The coefficient of variation of the static axial spray distribution was 33% based on liquid collection. The coefficient of variation of axial and radial spray distribution of P1 and P2 (based on coverage rate) were 37.2% and 58.3%, as well as 46.3% and 69.4%, respectively. This confirmed that the motion direction of the boom strongly influenced the spray distribution. The structure of the airflow also affected the radial spray distribution. Moreover, the axial spray distributions of both spray patterns had high correlation coefficients of 0.921 and 0.889 with a static distribution detected in the laboratory. Optimizing the configuration of the nozzles and airflow of the boom is expected to further improve the uniformity of the radial and axial spray distributions. This autonomous air-assisted sprayer based on single hanging track provides a predictable solution for plant protection in solar greenhouses.