High accuracy is often required to recognize the mud-adhered water chestnuts in the conveying stage of harvesters. However, it is still challenging under complex situations, such as soil adhesion and occlusion by soil clods during identification. In this study, an improved recognition was proposed for the water chestnut using RT-DETR-L (Real-Time Detection Transformer Large). Firstly, a Wavelet Transform Hybrid Group Block (WTHGBlock) was adopted to optimize the backbone network for the discriminative power of the target features. Secondly, a Multi-scale Head Dynamic Interaction Attention Feature Integration module (MSHD-AIFI) was constructed to recognize the small targets for the multi-scale performance. Three-level "local, medium, and global" branches were used to capture the features of varied sizes. The weights were adjusted dynamically. Finally, a Biqi Morphology-aware IoU Loss (BM-IoU Loss) was also introduced to incorporate the morphological constraints, size weighting, and region optimization. The localization deviations were then reduced due to the morphological similarity and occlusion. Each module was verified in the recognition task of the water chestnut under cluttered soil conditions. The RT-DETR-L was used as the baseline model. Three modules were designed for the ablation experiments. In the WTHGBlock module, the precision, recall, and mAP0.5 reached 85.0%, 91.1%, and 94.3%, respectively, which were improved by 1.2, 0.7, and 1.0 percentage points, compared with the baseline model. In the MSHD-AIFI module, the recall and mAP0.5 reached 91.3% and 93.6%, respectively, which were improved by 0.9 and 0.3 percentage points over the baseline, while the precision decreased by 0.7 percentage points. The perception of the small targets and occluded areas was enhanced after multi-scale dynamic attention. But the background noise also led to a slight increase in the false detections. In the BM-IoU Loss module, the precision, recall, and mAP0.5 were 84.4%, 91.7%, and 93.4%, respectively, which were improved by 0.6, 1.3, and 0.1 percentage points over the baseline RT-DETR-L model. When all three modules were integrated into the baseline RT-DETR-L model, the RT-DETR-L-WMB model achieved optimal performance, with the improvements of 1.4, 1.8, and 1.6 percentage points, compared with the baseline model. Among the three modules, the WTHGBlock enhanced the feature discriminability, the MSHD-AIFI module improved the multi-scale coverage, and the BM-IoU Loss was used to improve the localization accuracy. Their functions jointly improved the performance of the recognition in the complex scenes. The RT-DETR-L-WMB model achieved a recognition precision, recall, and mAP0.5 of 85.2%, 92.2%, and 94.9%, respectively. Compared with the mainstream models of the YOLO series, these metrics were improved by 2.4～3.9, 0.9～1.7, and 3.4～4.1 percentage points, respectively. In terms of efficiency, the parameter count of the improved model was reduced by 10.9～23.8 M, whereas the speed of the detection increased by 1.0～6.7 frame/s, compared with the mainstream models of the YOLO series. The performance was significantly enhanced for the higher detection speed with fewer computational resources. The actual target regions were much more focused on the heat map. Experiments show that the RT-DETR-L-WMB model achieved low missing or false detection in the complex scenarios with the densely stacked water chestnuts or backgrounds mixed with the soil clods. The parameter count and recognition speed of the improved model were 34.7 M and 41.9 frame/s, respectively, fully meeting the real-time and lightweight requirements for the water chestnut picking scenarios. This finding can provide some technical support for picking and sorting the tuber crops, such as water chestnut.

This study aims to separate the soil and corm while harvesting water chestnuts on dry land. A spring roller device of soil-corm separation was also designed for the water chestnut harvester, in order to reduce the injury rate of water chestnut. Positive and negative rotating springs were arranged side by side. During the operation of the harvester, the soil-corm mixture was dug out and passed through the lifting device and rubber-roller soil removal device, and then fell into the spring roller soil-corm separation device, where the water chestnuts were further separated from the soil under the vibration and rubbing of the rotating positive and negative spiral spring rollers. The kinetic analysis was performed on the relative motion of the water chestnut and spring roller. The influencing factors on the separation performance were determined as the spring outer diameter, pitch, adjacent spring spacing, height difference and spring speed, line diameter and operation speed. The simulation of soil-corm separation was carried out to optimize the operating performance of the spring roller. The model was then established using EDEM software, including three particles: large soil clods, water chestnuts and fine-grained soil. A single-factor test was carried out on the structural and working parameters of the spring roller, in order to clarify the influence of each factor on the soil-corm separation. Taking the sieving rates of water chestnut and soil as the test indexes, the quadratic regression orthogonal test was also carried out. An optimal combination of parameters was obtained for the spring roller, where the outer diameter was 100 mm, the pitch was 30 mm, the spacing was 9 mm, and the rotational speed was 420 r/min. The better performance was achieved, where the sieving rates of water chestnut and soil were 80%, and 80.69%, respectively. The verification tests were then conducted to compare the prediction of the model. The average relative errors of water chestnut and soil sieving rate were 2.09%, and 2.42%, respectively. The simulated harvesting and one-way tests were carried out to take the test indexes as the rates of the open, the injured, the peeling, and the digging, with the soil moisture content and spring speed as test factors. Among them, the water chestnuts were pre-buried into the soil layer and then harvested. Three wire diameters of springs of 10, 12, and 14 mm were also selected to evaluate the mud-fruit separating of spring rollers. It was found that the 12 mm wire diameter spring shared both better vibration performance and lower damage rate of water chestnut. Actual harvesting tests were conducted to test the performance of the soil-corm separating device. The performance of the water chestnut harvester was measured as follows: the operating speed was 0.21 m/s, the operating efficiency was 0.19 m²/s, the soil breaking rate was 75.61%, the open water chestnut rate was 82.42%, the injured water chestnut rate was 14.73%, and the peeling water chestnut rate was 7.01%. The soil crushing and soil-corm separation were enhanced with the increase in rotational speed. However, the injury rate of the water chestnut also rose, and the rotational speed of the spring roller should not be more than 244.5 r/min. The broken soil rate was outstandingly improved with the reduction of soil moisture content, but the injured rate of water chestnut increased as well. The damage rate of water chestnut more outstandingly increased with the decrease of soil moisture content at the soil moisture content of 15.77% to 17.44%, compared with the soil moisture content of 17.44% to 19.40%. The finding can provide a strong reference for the development and optimization of water chestnut harvester.

Large-scale mutton processing is ever-expanding with the increasing demand for meat production. Mechanized carcass segmentation has been one of the key steps to upgrade the mutton industries. Among them, the goat rib has been the main obstacle during segmentation. A scientific and reliable discrete element model of goat rib can be expected to provide both the analysis of mechanized goat carcass segmentation and the optimization of tool parameters. Taking the chilled Boer goat rib as the research object, this study aims to calibrate the discrete element parameters of the bending failure model using EDEM software. Firstly, a series of tests were carried out to determine the profile, density, Poisson’s ratio, and shear modulus of the goat rib. Next, the collision, inclined plane friction and friction coefficient measurement tests were conducted to measure the contact parameters, such as static friction coefficient, rolling friction coefficient, and collision recovery coefficient. The bending failure test of the goat rib was carried out on the texture analyzer to obtain the peak failure force and cutting position, which were the target values of the simulation. According to the actual test conditions, the discrete element model of goat rib was established to simulate the bending failure using Hertz-Mindlin with the bonding model in EDEM software. The path of the steepest ascent was used to determine the optimal parameters, including the optimal value of bonding parameters. A quadratic polynomial regression model was then optimized between the peak failure force and the four bonding parameters using response surface analysis. The optimal combination of four significant influencing factors was also obtained to solve the regression equation. The results illustrated that the normal stiffness per unit area was 7.07×10¹³ N/m³, the shear stiffness per unit area was 6.22×10¹² N/m³, the critical normal stress was 1.34×10⁸ Pa, and the critical shear stress was 1.87×10⁸ Pa. Finally, the bending failure of five goat ribs was simulated to verify the accuracy and reliability of calibration. The maximum relative error between the simulated and the actual values was less than 6.49%, and the average relative error was 4.19%, indicating the credible calibration. This finding can also provide a theoretical basis for parameter optimization in the mechanized segmentation of goat rib during mutton processing.