Soft pneumatic grippers: Topology optimization, 3D-printing and experimental validation

2025-11-24

AI Summary

To address insufficient modeling of pneumatic load dependency in soft pneumatic gripper design, this paper proposes a physics-informed topology optimization framework. It jointly models pneumatic loads using Darcy’s law and a drainage term, and employs a robust min-max strategy to concurrently optimize structural layout and erosion parameters. Leveraging Ogden hyperelastic constitutive modeling within finite element analysis and the Method of Moving Asymptotes (MMA), the approach first designs 2D compliant mechanisms and then extends them to 3D-printable, modular multi-arm architectures. The resulting gripper exhibits excellent controllable deformation across a wide pressure range and successfully manipulates diverse objects—irregularly shaped, variable-stiffness, and variable-weight—demonstrating strong adaptability and robust grasping performance.

Technology Category

• Intelligent Robots: Manipulation
• Search and Optimization: Sampling/Simulation-based Search
• Constraint Satisfaction and Optimization: Satisfiability Modulo Theories

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Experiences and lessons learnt from Web-based algorithms and system deployments
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Responsible Web: Machine-in-the-loop, human agency and autonomy

Abstract

This paper presents a systematic topology optimization framework for designing a soft pneumatic gripper (SPG), explicitly considering the design-dependent nature of the actuating load. The load is modeled using Darcy's law with an added drainage term. A 2D soft arm unit is optimized by formulating it as a compliant mechanism design problem using the robust formulation. The problem is posed as a min-max optimization, where the output deformations of blueprint and eroded designs are considered. A volume constraint is imposed on the blueprint part, while a strain-energy constraint is enforced on the eroded part. The MMA is employed to solve the optimization problem and obtain the optimized soft unit. Finite element analysis with the Ogden material model confirms that the optimized 2D unit outperforms a conventional rectangular design under pneumatic loading. The optimized 2D unit is extruded to obtain a 3D module, and ten such units are assembled to create a soft arm. Deformation profiles of the optimized arm are analysed under different pressure loads. Four arms are 3D-printed and integrated with a supporting structure to realize the proposed SPG. The gripping performance of the SPG is demonstrated on objects with different weights, sizes, stiffness, and shapes.

Problem

• Developing topology optimization for soft pneumatic grippers with design-dependent loads
• Creating 3D-printed soft arms using optimized 2D units and assembly
• Validating gripper performance on diverse objects through experimental testing

Innovation

• Topology optimization framework for soft pneumatic gripper design
• 3D printing assembly of optimized units into functional gripper
• Experimental validation on diverse object characteristics