## 3 Results
### Static Grasping  
A static grasping experiment was conducted with four comparative test groups to assess the feasibility of the proposed method. For each group, the number of oysters on a stationary conveyor belt was gradually increased. Fifteen tests were performed for each group, with a randomly selected number of oysters used for each test. If the robot failed to sort an oyster during a test, the sorting process continued until all oysters within its field of view were successfully sorted. Due to the limited field of view of the robot when detecting objects, any oyster accidentally removed from the field of view would have to be manually repositioned. Figure 7 shows part of the robot gripping process. Figure 7a-f show the sequence of the sorting process: the gripper of the robot starts from the starting position and then moves \begin{table}
\begin{tabular}{l l l l l} \hline
**Backbone** & **Parameters** & **GFLOPs** & **Precision** & **mAP50-95** \\ \hline YOLOv8s & 11422166 & 29.6 & 99.96\% & 0.858 \\ MobileNet V4 & 5703667 & 20.0 & 99.87\% & 0.847 \\ MobileNet V3 & 10710268 & 21.7 & 99.89\% & 0.861 \\ MobileNet V2 & 8481142 & 22.1 & 99.88\% & 0.853 \\ Shufflenetv1 & 8476998 & 18.9 & 99.94\% & 0.856 \\ Shufflenetv2 & 7611250 & 19.6 & 99.91\% & 0.851 \\ YOLOv11s & 9744931 & 22.7 & 99.99\% & 0.879 \\ \hline \end{tabular}
\end{table} 
Table 1: Training results of two models. Figure 6: Comparison of detection results between the original model and the optimized model (The red box is the rotation box that identifies the oyster). to the gripping point above the oyster after recognition. The gripper remains parallel to the conveyor belt and rotates to the corresponding grasping angle before moving vertically downward to a fixed height. After closing the gripper, the robot lifts the oyster to a certain height to ensure it is fully detached from the conveyor belt surface, then moves to the placement point to complete the sorting process. In Figure 7g, the object detection results are displayed, with each oyster showing a recognition confidence above 0.8. This indicates high recognition accuracy and precise calculation of the grasping point and angle for each oyster. During actual deployment, a confidence threshold mechanism was added: prediction and grasping are only executed when the confidence remains above 80 for 20 consecutive frames. According to the data in Table 2, the static grasping experiment consisted of four test groups, each with a progressively increasing number of oysters, and each group was tested 15 times. In each test, the robotic arm attempted to grasp all oysters within its field of view. By analyzing the results of the experiment, out of the total 157 grasping operations, 150 were successful, with a success rate of 95.54%. From the data of each group, the success rate of grasping decreased slightly as the number of oysters increased, which indicates that there may be some challenges in multi-object scenarios, especially when the number of oysters increases, and the following problems may be encountered: instability in object detection and interference in the movement of the gripper claws due to the close arrangement of oysters. Specifically, the grasping success rates of both Group 1 and Group 2 were 100%, which indicated that the robotic arm's grasping performance was very stable when the number of oysters was small. However, as the number of oysters increased, the grasping success rates of Groups 3 and 4 decreased to 95.74% and 92.30%, respectively. This decline can be attributed to several factors: first, the robotic arm may have difficulty in recognizing multiple targets, especially when the oysters are occluded from each other; second, the action of the grasping jaws may be affected by the positions and rows of other oysters, which may lead to some of the grasping failures. Overall, despite the fluctuating performance of the robotic arm in high-density object environments, the overall success rate of 95.54% indicates that the system still has high reliability in static grasping tasks.