Force Sensing and Force Control of Flexible Gripper with Integrated Flexible Strain and Tactile Sensors for Strawberry Non-Destructive Gripping and Freshness Grading

Fruit freshness detection is essential for ensuring fruit quality, with significant implications for the economic benefits and resource allocation in the supply chain. Current strawberry freshness detection methods, primarily based on machine vision or manual inspection, face challenges such as environmental sensitivity, high costs, labor shortages, and difficulties in quantitative assessment. To address these limitations, this study introduces a flexible robotic gripper integrated with strain and tactile sensors, which offers precise, non-destructive gripping and real-time freshness grading. The integration of strain sensors enables real-time force sensing, ensuring adaptive and safe handling, while tactile sensors measure strawberry firmness, providing a quantitative and objective assessment of freshness. A fuzzy adaptive PID controller regulates the gripper’s output force, further enhancing precision. Experimental results demonstrate a 97.6% safe gripping rate and classification accuracies of 87.5% (KNN), 93.75% (SVM), and 87.5% (RF), with SVM achieving the highest precision. This study features high environmental stability and durable robotic grippers and sensors and achieves automated, non-destructive sorting and high-quality grading. By leveraging technological innovations to address labor shortages and enhance fruit quality, this study contributes to a more efficient and sustainable supply chain.