Investigating effects of interaction of single tine and rotating tine mechanism with soil on weeding performance using simulated weeds

Abstract

<p>Mechanical weeding augmented with automation technology should results in highly effective weeding systems. However, the interaction between controlled weeding mechanisms and soil and weeding performance is not well understood. Moreover, soil is highly variable and makes studying this interaction challenging. The main objective of this research was to develop a method to investigate the effects of mechanical tool-soil interaction on weeding performance for different operating conditions in a controlled environment. Experiments were conducted in an indoor soil bin with loam soil, and the weeding performance was studied using small wooden cylinders as simulated weed plants. The investigations featured a single cylindrical tine and a rotating tine mechanism, vertically-oriented and inserted into the soil. Total width of soil disturbance and potential weeding rate were evaluated for the single cylindrical tine at different levels of operational factors namely: tine diameter (6.35 mm, 7.94 mm and 9.53 mm), working soil depth (25.4 mm, 50.8 mm and 76.2 mm) and tine speed (0.23 m/s and 0.45 m/s). Potential weeding rate was examined for the rotating tine mechanism across two operational factors: working soil depth (25.4 mm and 76.2 mm) and rotational speed (25, 50 and 100 rpm). Statistical analysis was performed using ANOVA at p < 0.05. A simulation of the rotating tine mechanism was developed which estimated disturbed area. For the single tine, soil disturbance width was independent of the test speeds; however, diameter and depth had significant effects as the width increased with increased levels of these two parameters. All three parameters had significant effects on potential weeding rate of the single tine, and the rates were observed to increase for higher levels of the operating parameters. For the rotating tine mechanism, both depth and rotational speed were significant. The potential weeding rate for the mechanism was found to increase for higher levels of these parameters. The results showed that although the width of soil disturbance due to a cylindrical tine are affected by tine diameter and working soil depth, operating parameters such as increased longitudinal and rotational speeds also affect plant disturbance. The percentage of disturbed soil area in simulation followed similar patterns as the percentage disturbed plants observed in the experiments.</p>