Application of leaf attitude sensor systems in air-assisted spraying operation in cowpea and citrus

In air-assisted spraying operations, the leaves are perturbed by the airflow and undergo attitude changes, the droplets are deposited onto the leaf surface with the assistance of the airflow. To explore the process, it is important to obtain the dynamic attitude characteristics of the leaves. Therefore, in this study, a leaf attitude sensor was developed that could output the deflection angle data of the leaf in the x-, y- and z-axes accurately. The output frequency of the sensor was 0.2–200 Hz and applied to cowpea and citrus spraying operations. The leaf deposition and leaf deflection angles were acquired simultaneously to explore the relationship between them. Results revealed that in cowpea spraying, the coverage of the abaxial leaf surface had a significant negative correlation with the deflection angle on the x-axis and a positive correlation with the z-axis. For the upper and middle canopies of a citrus tree, a negative correlation was discovered between the coverage of the abaxial leaf surface and the deflection angle of the x-axis. In summary, the sensors developed in this study can be used to obtain leaf deflection angles during spraying operations. The obtained data can provide support for analysing the process of droplet deposition onto the leaves and improving the spray effect. The sensor developed in this study can be used to investigate the relationship between deposition and leaf oscillation during spraying, thereby providing theoretical and data support for the improvement of application equipment and parameters.