Parameter calibration of poplar seeds based on EDEM and experimental verification of repose angle

During automated handling of poplar seeds for phenotypic measurement, an improperly designed or operated air conveying system can lead to reduced efficiency, choking, and batch-to-batch cross-contamination due to incomplete discharge. To address the lack of discrete element method (EDEM) parameters for poplar seeds, three cultivars (Populus pseudo-simonii, Populus × euramericana CL. ‘Zhonglin46’, and Populus deltoides × P. euramericana cv. ‘Nanlin895′) were selected for parameter calibration, providing the input required for conducting computational optimization, as traditional experimental methods are insufficient to reveal the underlying particle flow mechanisms. Physical experiments determined the coefficients of restitution (0.489, 0.428, and 0.391), static friction (0.462, 0.503, and 0.564), and rolling friction (0.141, 0.177, and 0.256) against an acrylic plate. The Steepest Ascent Test and Central Composite Rotatable Design were employed to develop Response Surface Models and optimize simulation parameters, yielding optimal inter-particle coefficients, including restitution (0.302, 0.564, and 0.563), static friction (0.540, 0.495, and 0.684), and rolling friction (0.218, 0.184, and 0.154). Validation yielded relative errors of 0.94%, 2.21%, and 2.92% between simulated and actual angles of repose, respectively. The calibrated parameters enable reliable simulation of millimetre-sized seed handling, supporting the development of automated phenotyping systems.