Design, Fabrication and Evaluation of a Mobile Robot for Spraying in Greenhouses

In recent years, researchers have tried to develop robots for agricultural applications. Robots make it possible to reduce human exposure to pesticide application risk. The aim of this research was to develop an automated method of spraying of plants in greenhouses. A threewheel differential steering vehicle was designed and constructed to act as the greenhouse sprayer. Power was transmitted from two DC motors to two drive wheels through a gearbox and shaft system. A proportional controller was developed and tested to control the left and right motors, which navigated the aisles using information provided by ultrasonic sensors.After design and fabrication, the robot was tested on concrete surfaces at 0.15, 0.25 and 0.35 m/s inside a greenhouse along a U-shaped path 0.98 m in width. Spraying, safety and obstacle detection units of the vehicle were evaluated. The tests results showed that the average RMSE of the vehicle position was between 4.93 and 6.51 cm at different speeds. Increasing the speed increased the RMSE of the vehicle position. The performances of the safety and central station units of the vehicle were acceptable. The accuracy of the spray function was 99.47% and the no-spray function was 99.92%, which are acceptable for greenhouse applications.