Optimal Design and Analytical Modeling of a Soft Fin-Ray Effect Gripper Finger Using the Finite Rigid Elements Method

2026-06-02

AI Summary

This study addresses the challenge of simultaneously achieving compliance and precise force control in soft robotic grippers when handling fragile and irregularly shaped objects. The authors propose a soft gripper finger based on the Fin Ray effect and develop a high-fidelity analytical model using the Finite Rigid Element Method (FREM). The model is validated through ANSYS finite element simulations and physical experiments. Through multi-objective optimization, optimal structural parameters are identified: a length of 30 mm, rib spacing of 10 mm, seven ribs inclined at −15°, and a thickness of 1 mm. The FREM model achieves a deformation prediction error of only 3%, while ANSYS simulations exhibit an error as low as 2%, thereby establishing a robust foundation for the development of high-precision force controllers.

Abstract

Fin Ray-inspired soft grippers offer a promising solution for gently handling delicate, irregular objects, especially in agriculture. The objective of this research is to design, fabricate, and model a Fin Ray Effect (FRE) soft gripper finger to enable precise force control in future applications. This design aims to gently grasp delicate agricultural products, such as tomatoes, that require both adaptability and accurate force application. To address the inherent challenges of soft robotics, including nonlinear behavior, infinite degrees of freedom, and variable material properties, the Finite Rigid Elements Method (FREM) was employed for modeling. This method preserves analytical accuracy while providing a reliable foundation for the development of a force controller in later stages. A detailed Finite Element Model (FEM) was created using ANSYS, and the analytical results were validated through simulation and experimental testing. The gripper's fingers were optimized based on four key criteria: tip displacement, total deflection, stress distribution, and contact force. The optimal finger configuration includes a length of 30 mm, rib spacing of 10 mm, seven ribs angled at -15 deg, and a rib thickness of 1 mm. Theoretical modeling using the FREM predicted finger deformation with a 3% error, while the ANSYS numerical model achieved 2% error.

Problem

• soft gripper
• Fin Ray Effect
• force control
• delicate object handling
• agricultural robotics

Innovation

• Fin Ray Effect
• Finite Rigid Elements Method
• soft gripper
• analytical modeling
• force control