Design and test of intelligent spraying unmanned vehicle for greenhouse tomato based on YOLOv4-tiny

Unmanned vehicle for spraying is used in production of facility agriculture and smart agriculture. Tomato in greenhouse has characteristics of narrow planting spacing and many twisted lead wires, which required special vehicles. Therefore, it is necessary to design a miniaturized, variable, and intelligent spraying unmanned vehicle for greenhouse tomato. It is mainly composed of a disease detection and positioning module, a lifting platform, a steering gear rocker mechanism, and a fully automatic bearing chassis. This design innovatively combines deep learning technology to achieve automatic detection of disease targets. RGB image of greenhouse tomato collected by Kinect V2 was used as input for disease detection. Two-dimensional pixel coordinates of the disease detection results were converted into three-dimensional spatial coordinates for realizing disease location. Ball screw and stepping motor were used to adjust height of the lifting platform. Then, the steering gear rocker mechanism was employed to locate disease of the greenhouse tomato. Variable and intelligent spraying was thus completed. Results showed that target detection accuracy of fruit clusters and diseases in complex environment reached 75.15% with F1 score of 79.96 through testing the trained YOLOv4-tiny model. It detected 37.6 images per second, so it was able to be deployed on the embedded development board to detect disease targets of greenhouse tomato. Compared with the results of manual disease location, results showed that absolute error of disease location was within ±3.5 cm. Through field test of the spraying unmanned vehicle, the success rate of the whole machine of the intelligent spraying unmanned vehicle for greenhouse tomato was above 75%, and the error rate of spraying pesticide was below 20%, which achieved accurate positioning of diseases of greenhouse tomato and variable intelligent spraying according to disease degree. This design can provide reference for the design of other spraying unmanned vehicle and has a good promotion and application prospect.