Evaluation of a Leveling System for a Weeding Robot under Field Condition

Weed control is a huge problem in organic vegetable farming. Even though there are machines available for inter-row weeding, manual weeding is the only choice for adequately controlling weeds, particularly in the space between plants (also called intra-row weeding). Unfortunately, manual weeding is highly labor intensive and costly. Robotic or automatic weeding would be one of the potential solutions for solving the problem. However, some of the technical challenges need to be removed for automatic weeding. One of such technical challenges is that the weeding end-effector needs to reach target precisely to remove weeds located very close to the plant while the robotic vehicle is continuously moving on a generally uneven and uncertain field surfaces. This study was aimed at assessing the performance of an end-effector auto-leveling system designed to accurately control the position of weeding end-effectors during field operations in vegetable crops. The performance assessment was conducted via a set of field experiments using a specifically designed and fabricated robotic platform with leveling system. To achieve the desired level of performance in actual field conditions, the prototype system required to maintain the end-effector base at horizontal position within a +/- 0.25 degrees angular error when the prototype is operating under a field condition causing up to -11 degrees to 11 degrees variation in roll and pitch angles. The test results verified that the developed end-effector base leveling system could maintain the drift of the end effector tip position within 18 mm, and maintain the roll and pitch angular error within 0.2 degrees. Meanwhile, based on the concept of proof research, it is safe to say the corresponding position error caused by angular error of the leveling plate was limited in 1 mm when the leveling plate at a height of 50 cm under field condition. The experiment results can prove that the leveling system can efficiently reduce the effect of the rough field. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.