Weed overgrowth in high-value crops like onions remains a major challenge due to labor costs, herbicide resistance, and environmental concerns. Robotic laser-based weed control offers a precise, chemical-free alternative capable of targeting individual weeds while protecting crop health and the environment. This research introduces the application of a Clavel-based delta parallel robot for precision weed elimination using a high-power diode blue light laser. The delta robot employed in this study features three degrees of freedom and is capable of achieving maximum accelerations up to 20 m/s². It consists of aluminum proximal arms connected to servo motors and carbon fiber distal arms, reducing weight and enhancing agility. These servo motors are housed within a top base constructed from ABS 3D printed parts. Movement calculations and inverse kinematics are managed by an embedded ARM Cortex-M3 controller integrated with the servo motors. A 450 nm, 10W diode laser serves as the robot's end-effector, actuated using the Transistor-transistor logic (TTL) signals. Both robot movements and laser activation are simultaneously controlled through an external Arduino Mega 2560 microcontroller, leveraging a custom-developed C library to ensure workspace safety and precision. Experiments conducted to assess positional accuracy involved 100 trials, resulting in a mean radial positional error of 0.83 mm. Further experiments measured laser exposure time and stand-off distance. The results showed complete weed destruction in less than 6 seconds at distances of up to 100 mm. These results support the robot's effectiveness in targeted weed management for precision agriculture.
