Performance of Planter Electric-drive Seed Meter during Simulated Planting Scenarios
Authors: Strasser Ryan , Badua Sylvester , Sharda Ajay , Mangus Devin , Haag Lucas 
Published: December 2019

Highlights.

Seed meter rpm error decreased with increasing planter speed during steady states.

Point-row operations could result in up to 10-13 seeds being over- or under-planted.

Seed meter rpm error varied from -7.2% to 7.9% during curve planting transient states.

Abstract. Electric drive seed metering systems have become a common method for singulating row crop seed. These singulation systems have substantially fewer moving parts and can potentially respond more quickly than other drive mechanisms. However, the accuracy and response time of these systems has yet to be examined to quantify potential benefits of adoption. The objectives of this study were (1) to quantify accuracy and response time of electric meter drives to varying ground speeds and speed transitions during in-lab simulation planting operations on straight-line and curves, and (2) to compare actual seed meter motor speed to target meter speed during simulation field scenarios. To quantify metering system performance, test scenarios were developed to simulate planting on headlands, within field boundaries including traversing in-field obstacles, and planting on curves with different radii. Ground speeds during simulation scenarios were 7.2, 12.9, and 16.1 kph when operating on straight rows and 6.0, 8, 11, and 14.5 kph when planting along curvilinear paths. Test scenarios also included planter acceleration and deceleration at 0.4 and 0.6 m/s2 when traversing in-field obstacles and tighter radii curves. Tests were conducted with two different seeding rates, 44,460 and 88,920 seeds/ha. Eight high frequency encoders were mounted on the electric meters of selected row units to record real-time meter rpm and quantify seed meter accuracy and response time. A custom DAQ system was developed to read simulation test scenario data files in ASCII text file format and send prescribed ground speed commands to the Horsch Maestro 24.30 planter’s ECU at 10 Hz using a program written in LabVIEW. Results indicated that seed metering accuracy increased as ground speed increased resulting in a significantly lower seed meter rpm error at 16.1 kph under steady-state conditions. During transient states, seed meters needed 3 to 4 s to respond during deceleration and acceleration resulting to seed meter rpm error ranging from -3.7% to 3.6% at 44,460 seeds/ha seeding rate and from -3.8% to 3.2% at 88,920 seeds/ha seeding rate. During point-row operations, the response time of the meters was 0.4 s which could result in up to 10 seeds being under-planted and up to 13 seeds being over-planted per row unit. During curvilinear planting, seed meter rpm error for steady states ranged from -0.5% to 0.8% across varying turn radii resulting to seeding rate error ranging from -223 to 370 seeds/ha while during transient states seed meter rpm error varied from -7.2% to 7.9% resulting to seeding rate error ranging from -5,886 to 7,187 seeds/ha. Keywords: Seed meter rpm, Seeding rate error, Simulation, Variable rate planting, Planter meter.