Analytical Design and Test of Licorice Harvester Based on DEM–MBD Coupling

This study addresses the issues of high operating resistance, incomplete separation in ascending transport chains, and significant wear and tear in existing licorice harvesters. A new licorice harvester has been designed that incorporates a lift chain conveyor separation device, enabling excavation, separation, collection, and centralized stacking to be completed in a single operation. The paper describes the harvester’s overall structure and provides detailed analyses and designs of its key components, including the digging shovel, roller screen, conveying and separating screens, and soil-crushing roller. Multi-body dynamics (MBD) and discrete element models (DEM) for licorice and soil were developed, and the entire harvesting process was simulated using the coupled DEM–MBD method to analyze the trajectory and speed of the licorice. Field tests confirmed that the conveyor separation screen operates smoothly, effectively separates licorice rhizomes from soil, and minimizes damage to the licorice. Field test results show a net digging rate of 96.2%, a damage rate of 4.3%, and an average digging depth of 580 mm. The operational indexes meet the standards for harvesting root and stem Chinese herbal medicines. The machine operates stably and exhibits exceptional conveying and separating effects, demonstrating its suitability for mechanized harvesting of root and stem herbs.