Design, Fabrication, and Experimental Investigation of Screw Auger Type Feed Mechanism for a Robotic Wheat Drill

Abstract

Highlights An auger-type feed mechanism was designed for a robotic wheat drill, and a laboratory investigation was carried out. To avoid seed blockage, the recommended screw auger pitch must be at least 150% of the maximum seed dimension. The performance of the feed mechanism was influenced by auger speed, vibration, and slope. This study delivered a bulk feed mechanism for wheat drilling, which can be easily scaled and adopted by small autonomous vehicles or mobile robots. Abstract. Cultivating the arable, highly sloped hills and uneven terrain is challenging and unsafe with large agricultural machines. Therefore, a fleet of small autonomous ground vehicles (AGVs) was proposed to farm sloped or uneven terrain. The fleets need a robotic grain drill to operate on varying slopes, and the success of the fleet depends on the performance of the robotic seeder or grain drill. The feed mechanism is the heart of the seeder, and its design and performance influence the plant population and crop yield. In this study, we designed and fabricated an auger-type feed mechanism for robotic wheat drilling. Feed mechanisms with augers having three different pitches were developed as per the ASABE standards. The developed feed mechanism was investigated in a laboratory setup for flow rate and flow uniformity in accordance with ISO standards. The predictor variables were auger type (pitch), auger rotational speed, vibration, and slope. The auger flow rate for flat slopes was a linear function of auger speed and varied from 30 g/min to 170 g/min. The coefficient of variation (CV) for the flow rate ranged from 2% to 10%. The CV was within acceptable limits, which was an excellent indicator of the bulk feed mechanism's flow uniformity. The performance of the feed mechanism was influenced by vibration and slope. However, the auger flow rate remained constant for vibration frequencies of 0, 6, and 14 Hz, suggesting that the feed mechanism was vibration-proof and could tolerate the vibration frequency up to 14 Hz. The flat, downhill (descending), and uphill (ascending) slope levels did not affect the feed mechanism performance. However, the side slopes (right and left slope) significantly affected the feed mechanism flow rate but did not affect the flow uniformity. The study also developed a feed mechanism for a sloped-ground prototype seeder, which can be easily scaled and adopted by small autonomous vehicles or mobile robots. Keywords: Flow rate, Flow uniformity, Multi-robot, Robotic seed drill, Screw auger, Seed rate.