Micro-modelling of tomato pericarp and simulation of the ripeness-related mechanical properties for advanced robot harvesting

The application of fruit harvesting robots is becoming increasingly mature. However, the utilization of fruit macroscopic mechanics as the picking threshold in the robotic end-effector may result in fruit damage, as the internal microscopic mechanics of the fruit may have varying stress thresholds. This work proposed a modeling method for the micro-analysis of tomato fruit peel based on image processing techniques. Leveraging programming techniques, optical microscopic images of fruit peel cell tissue are obtained and processed to extract the porous structure, enabling the subsequent reconstruction of geometric models. An enhanced generalized Maxwell model is employed in this study, wherein INP files were autonomously generated through programming and imported into Abaqus for microscale mechanical simulation analysis of fruit peel. Based on this methodology, it was possible to simulate the viscoelastic mechanical behavior of fruit peel solely through the optical tissue images. By examining the stress relaxation curves of fruit peel, a more comprehensive understanding of the microscopic mechanical behavior of the fruit was attained. This study contributed to providing a more precise reference standard for the gripping force threshold during robotic harvesting, thereby enhancing the efficiency of harvesting robot.