Characteristics of unmanned aerial spraying systems and related spray drift: A review

Abstract

Although drift is not a new issue, it deserves further attention for Unmanned Aerial Spraying Systems (UASS). The use of UASS as a spraying tool for Plant Protection Products is currently explored and applied worldwide. They boast different benefits such as reduced applicator exposure, high operating efficiency and are unconcerned by field-related constraints (ground slope, ground resistance). This review summarizes UASS characteristics, spray drift and the factors affecting UASS drift, and further research that still needs to be developed. The distinctive features of UASS comprise the existence of one or more rotors, relatively higher spraying altitude, faster-flying speed, and limited payload. This study highlights that due to most of these features, the drift of UASS may be inevitable. However, this drift could be effectively reduced by optimizing the structural layout of the rotor and spraying system, adjusting the operating parameters, and establishing a drift buffer zone. Further efforts are still necessary to better assess the drift characteristics of UASS, establish drift models from typical models, crops, and climate environments, and discuss standard methods for measuring UASS drift.

Keywords: downwash airflow; drift measurement; relative movement; spray drift; unmanned aerial spraying systems.

FIGURE 1

Examples of Hydraulic nozzles. (A) Hollow cone nozzle (TR80-02c, Lechler), (B) flat fan nozzle (HYPRO, 110-015), (C) air induction nozzle (IDK 120-01, Lechler).

FIGURE 2

Centrifugal nozzle (2018, XAG Co., Ltd).

FIGURE 3

The UASS spraying test bench in South China Agricultural University.

FIGURE 4

The relative position of the rotor and the nozzle. (A) Inside under the rotor (T30, from DJI), (B) below the rotor (extended, 3WWDZ-16, from Tuogong), (C) below the rotor (P30, from XAG), (D) boom (kongzhongbaoma, from SCAU).

FIGURE 5

The UASS with different numbers of rotors. (A) Eight-rotor UASS (MG-1P, from DJI), (B) quadrotor UASS (P30, from XAG), (C) six-rotor UASS (M45, from GKXN,China), (D) two-rotor UASS (V40, from XAG).