Calibration method and experimental verification of corn discrete element parameters

The calibration of discrete element contact parameters for corn is an important foundation for studying the interaction mechanism between grain silo robots and corn grain surfaces. The corn betwixt contact parameters were calibrated using the Box-Behnken experiment, with the corn betwixt repose angle as the response variable. Preliminary calibration of the contact parameters of corn-polylactic acid (PLA) was conducted through free-fall tests, as well as inclined sliding and rolling test. Using the principle of equivalence, experiments on the corn-PLA angle of repose were performed using the lifting and lateral collapse methods, leading to the establishment of a mathematical regression model to optimise the combination of corn-PLA contact parameters. The results indicated that the combination error of the corn betwixt contact parameters is 1.70%; the restitution coefficient of corn-PLA is 0.528, the static friction coefficient is 0.418, the rolling friction coefficient is 0.0383 and the verification error of the angle of repose is 2.58%, which is 3.83% lower than that before optimisation. Finally, the accuracy of the discrete element method model was experimentally confirmed using the driving velocity, displacement, body pitch angle and sinkage of the grain silo robot as indicators.