The objective of this study was to collect and interpret three-axis acceleration, temperature, and relative humidity data from six locations within commercial transport trailers shipping market-weight pigs. Transport was observed in Kansas (n = 15) and North Carolina (n = 20). Prior to loading, three-axis accelerometers were affixed to six locations on the trailers: top fore (TF), top center (TC), top aft (TA), bottom fore (BF), bottom center (BC), and bottom aft (BA) compartments. Data were post-processed to calculate root mean square (RMS) accelerations and vibration dose values (VDV) in the vertical direction and the horizontal plane. These values were compared to exposure action values (EAV) and exposure limit values (ELV), vibration levels deemed uncomfortable and potentially dangerous to humans. Additionally, RMS and VDV were compared among the trailer compartments. The vertical RMS accelerations for all compartments exceeded the EAV for loads measured in Kansas, and for the majority of the compartments measured in North Carolina. Many compartments, specifically the BA compartment from all trips, exceeded the vertical ELV. Regardless of where the data were collected, fewer compartments exceeded the EAV in the horizontal orientation. Only BA compartments exceeded the ELV in the horizontal orientation. There were Area × Level interactions for vertical and horizontal RMS and VDV (P < 0.01). The BF compartment had a greater vertical RMS value than the TF, TC, and BC (P < 0.02) compartments, but did not differ (P = 0.06) from the TA compartment. The vertical RMS of the TA compartment did not differ from the TF, TC, and BC compartments (P > 0.13). The BF compartment had a greater (P = 0.02) vertical VDV value than the TC location, but did not differ from the other locations (P > 0.16). All other locations did not differ in vertical VDV (P > 0.12). The BF compartment had greater horizontal RMS than the TC and TA compartments (P < 0.01), but did not differ from TF and BC compartments (P > 0.12). All other compartments did not differ in horizontal RMS (P > 0.34). All compartments, aside from the BA compartment, did not differ in horizontal VDV (P > 0.19). Vibration analyses indicated the BA compartment had the greatest vertical and horizontal vibrations and a large percentage of the compartments exceed the EAV and ELV, which indicated pigs may have experienced uncomfortable trips that could cause discomfort or fatigue.
Increased soybean (Glycine max L. Merril) seed costs have motivated interest in reduced seeding rates to improve profitability while maintaining or increasing yield. However, little is known about the effect of early-season plant-to-plant spatial uniformity on the yield of modern soybean varieties planted at reduced seeding rates. The objectives of this study were to (i) investigate traditional and devise new metrics for characterizing early-season plant-to-plant spatial uniformity, (ii) identify the best metrics correlating plant-to-plant spatial uniformity and soybean yield, and (iii) evaluate those metrics at different seeding rate (and achieved plant density) levels and yield environments. Soybean trials planted in 2019 and 2020 compared seeding rates of 160, 215, 270, and 321 thousand seeds ha−1 planted with two different planters, Max Emerge and Exact Emerge, in rainfed and irrigated conditions in the United States (US). In addition, trials comparing seeding rates of 100, 230, 360, and 550 thousand seeds ha−1 were conducted in Argentina (Arg) in 2019 and 2020. Achieved plant density, grain yield, and early-season plant-to-plant spacing (and calculated metrics) were measured in all trials. All site-years were separated into low- (2.7 Mg ha−1), medium- (3 Mg ha−1), and high- (4.3 Mg ha−1) yielding environments, and the tested seeding rates were separated into low (< 200 seeds m−2), medium (200–300 seeds m−2), and high (> 300 seeds m−2) levels. Out of the 13 metrics of spatial uniformity, standard deviation (sd) of spacing and of achieved versus targeted evenness index (herein termed as ATEI, observed to theoretical ratio of plant spacing) showed the greatest correlation with soybean yield in US trials (R2 = 0.26 and 0.32, respectively). However, only the ATEI sd, with increases denoting less uniform spacing, exhibited a consistent relationship with yield in both US and Arg trials. The effect of spatial uniformity (ATEI sd) on soybean yield differed by yield environment. Increases in ATEI sd (values > 1) negatively impacted soybean yields in both low- and medium-yield environments, and in achieved plant densities below 200 thousand plants ha−1. High-yielding environments were unaffected by variations in spatial uniformity and plant density levels. Our study provides new insights into the effect of early-season plant-to-plant spatial uniformity on soybean yields, as influenced by yield environments and reduced plant densities.
HighlightsLaying the groundwork for AGV mobility models for high slope terrain operations.AGV drawbar pull performance was evaluated on a level terrain, uphill, and downhill slopes up to 18° on a soil bin.AGV generates the optimum power efficiency with enough drawbar pull to perform a range of agricultural operations on uphill and downhill slopes up to 18°.Explored the suitability and established the boundary conditions of small size ground vehicles on the high slope farming.Generated sloped traction data would empower the multi-AGV system on sloped terrain.Abstract. Excessive steepness of grasslands, hills, or uneven terrain presents difficulties for farming with large conventional equipment. Therefore, a fleet of Autonomous Ground Vehicles (AGV) is proposed to perform primary agricultural operations on high sloped hills or terrain. However, it is imperative to understand how an individual AGV functions on sloping terrain under varying load and speed. Hence, this study aims to investigate the traction, mobility, and energy consumption characteristics of AGV on a sloped soil bin environment. A drawbar pull performance of the prototype AGV was evaluated on a level terrain and variable slope of 10° and 18°, both uphill and downhill, at varying drawbar pull (P) and AGV speed. The AGV’s performance metrics include power efficiency (PE), travel reduction (TR), and power number (PN) which relates to AGV’s traction, mobility, and energy usage, respectively. The AGV generated drawbar pull equivalent to its weight only on downhill run for reduced PE. On a level terrain (0°), the peak PE was 0.20 and was found to be 108.3% and 328.6% higher on 10° and 18° downhill run than uphill with 55.5% and 133% increase in drawbar pull, respectively. Both applied drawbar pull and uphill operation caused the AGV’s TR. The TR, corresponding to a peak PE, increased from 10% to 30%, respectively, on 0° and both 10° and 18° uphill. The optimum values of power number ranged from 2 to 4. The AGV delivers the optimum PE and generates enough drawbar pull with an optimum TR to perform a range of agricultural operations on a slope up to 18°. This study explored the suitability and established the boundary conditions of small size ground vehicles for high-sloped farming. Besides this, the study also aims to generate an AGV’s slope traction database to optimize its control variables, design optimization, and develop a mobility model for sloped terrain. Keywords: Drawbar pull, Ground vehicle, Multi-AGV fleet, Power efficiency, Slope, Travel reduction.
HighlightsAn 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.
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