Analysis of Deflection Angle and Actuation Capabilities of a Soft Knitted Gripper Employing an Equivalent Unit Cell Model

Muhammad Umar Elahi; Ju-Hee Lee; Min-Woo Han; Heung Soo Kim

doi:10.7734/COSEIK.2025.38.5.339

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2025 Vol.38, Issue 5 Preview Page Next Page

Research Paper

Analysis of Deflection Angle and Actuation Capabilities of a Soft Knitted Gripper Employing an Equivalent Unit Cell Model 등가 유닛 셀 모델을 이용한 소프트 니트 그리퍼의 변위 각도 및 작동 성능 분석

31 October 2025. pp. 339-346

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Abstract

Soft robotics offers enhanced flexibility, adaptability, and safety compared with traditional rigid-body systems, making it particularly suitable for applications involving human interaction and unstructured environments. Among the various actuation mechanisms developed for soft robots, shape memory alloy (SMA)-textile actuators have emerged as a promising solution owing to their lightweight, silent operation, and high energy density. This study investigates the actuation performance and deflection behavior of a soft knitted gripper fabricated using SMA-based textile actuators configured in a P-loop pattern. To model and predict the deformation behavior of the gripper, an equivalent unit cell (EUC) model was implemented in ABAQUS. This model was employed to analyze and compare the deflection capabilities of the soft knitted gripper against the EUC model. Geometric nonlinearity was incorporated to simulate large deformations resulting from the shape memory effect under electrical excitation. The analysis focused on the bending behavior of the P-loop structure, which is critical for effective gripping and manipulation tasks. Experimental validation was performed by applying varying voltages to the gripper and measuring the resulting deflection angles. Results indicate that increasing the applied voltage significantly enhanced bending, with maximum deflection angles up to 180°, demonstrating the actuator’s strong performance. Numerical simulations from the EUC model closely aligned with experimental results, with only a 5% deviation in maximum bending angle, thereby confirming the accuracy and reliability of the proposed modeling approach. This study demonstrates that the EUC model is exceptionally proficient in estimating the actuation behavior of SMA-textile-based soft grippers. The findings provide significant insights for the design and enhancement of next-generation soft actuators and underscore the potential of SMA-textile composites in modern soft robotic systems and biomedical applications requiring conformal, compliant actuation.

Keywords

bending angle prediction

knitted soft gripper

large deformation

shape memory alloys

textile actuator

소프트 로보틱스는 기존의 강체 시스템에 비해 향상된 유연성, 적응성, 그리고 안전성을 제공하며, 이는 특히 인간과의 상호작용이나 비정형 환경에서의 응용에 적합하다. 소프트 로봇을 위한 다양한 구동 메커니즘 중 형상기억합금(SMA)-섬유 액추에이터는 경량성, 저소음 작동, 높은 에너지 밀도 등의 장점으로 유망한 솔루션으로 부상하고 있다. 본 연구에서는 P-루프 형태로 구성된 SMA 기반 섬유 액추에이터를 사용하여 제작된 소프트 니트 그리퍼의 구동 성능 및 굽힘 거동을 해석하였다. 그리퍼의 변형 거동을 모델링하고 예측하기 위해 ABAQUS 환경에서 등가 유닛 셀(EUC) 모델을 활용하여 소프트 니트 그리퍼와 EUC 모델 간의 굽힘 성능을 분석 및 비교하였다. 해당 모델은 전기 자극에 따른 형상기억 효과로 인한 대변형을 시뮬레이션하기 위해 기하학적 비선형성을 포함하였다. 분석에는 P-루프 구조에서 나타나는 굽힘 거동이 포함하였으며, 이는 효과적인 파지 및 조작을 위해 중요한 요소이다. 실험적 검증은 다양한 전압을 그리퍼에 인가하고, 그에 따른 굽힘 각도를 측정함으로써 수행하였다. 실험 결과, 인가 전압이 증가함에 따라 굽힘 각도도 유의미하게 증가하였으며, 최대 180°까지의 변형이 관찰되어 액추에이터의 우수한 성능을 입증하였다. EUC 모델을 기반으로 한 수치 해석 결과는 최대 굽힘 각도에서 단 5%의 오차 범위를 보이며 실험 결과와 매우 근접한 양상을 나타내어, 제안된 모델링 접근법의 정확성과 신뢰성을 확인하였다. 본 연구는 EUC 모델이 SMA-섬유 기반 소프트 그리퍼의 구동 거동을 효과적으로 예측할 수 있음을 보여주었으며, 차세대 소프트 액추에이터의 설계 및 성능 향상을 위한 중요한 통찰을 제공하였다. 또한, 형상에 밀착되며 유연한 작동이 요구되는 현대 소프트 로보틱스 및 생체의료 응용 분야에서 SMA-섬유 복합재의 활용 가능성을 확인하였다.

키워드

굽힘 각도 예측

니트형 소프트 그리퍼

대변형

형상기억합금

섬유형 액추에이터

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Information

Publisher :Computational Structural Engineering Institute of Korea
Publisher(Ko) :한국전산구조공학회
Journal Title :Journal of the Computational Structural Engineering Institute of Korea
Journal Title(Ko) :한국전산구조공학회 논문집
Volume : 38
No :5
Pages :339-346
Received Date : 2025-06-26
Revised Date : 2025-07-13
Accepted Date : 2025-07-15
DOI :https://doi.org/10.7734/COSEIK.2025.38.5.339

Journal of the Computational Structural Engineering Institute of Korea ISSN:1229-3059(Print) 2287-2302(Online) 한국전산구조공학회 논문집

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