Design, Development and Optimization of a Robotic Weed Control System for Greenhouses

Abstract

This study presents the design and development of a robotic prototype specifically engineered for weed elimination within cucumber plants growing in greenhouse conditions. Given the limited research in automated weed control tailored to cucumber cultivation, this project fills a crucial gap in agricultural robotics. The cucumber plants are arranged in a single row, maintaining a spacing of approximately 40 cm between each plant, while the rows themselves are positioned about 1 meter apart. The greenhouse environment features sandy loam soil, which informs the robot's design and operational parameters. The robot employs three arrays of ultrasonic sensors strategically positioned to enhance weed detection capabilities. A PIC18 F4550-E/P microcontroller serves as the processing unit, enabling real-time feedback from the sensors that triggers the actuation of a robotic arm. This arm is engineered to maneuver between plant rows, utilizing rotating blades for efficient weed cutting. A comprehensive experimental procedure was conducted, comprising 54 trials within the greenhouse setting, to optimize the performance of the robotic arm. Key variables investigated included arm motor (AM) speed, blade rotation (BR) speed, and blade design. The research tested three BR speeds—3500, 2500, and 1500 RPM—determined based on prior literature concerning rotary movers. Furthermore, two AM speeds (10 and 30 RPM) paired with three distinct blade designs—S-shaped, triangular, and circular—were evaluated primarily for their cost-efficiency and performance based on initial testing outcomes. Results revealed a significant correlation between motor speed and weed cutting efficiency, showing that higher motor speeds correlated with a decreased percentage of cut weeds. Consequently, the 10 RPM motor speed was identified as the optimal setting for arm movement, balancing effective weed removal with operational efficiency.