Robots for Manipulation
Bio-integrated Robotics Lab
Robots for Manipulation
문어의 흡착판, 도마뱀의 미세섬모, 그리고 인간의 손에 이르기까지 — 자연은 물체를 조작하기 위한 매니퓰레이터 디자인에 무한한 영감을 제공합니다. 도마뱀은 발바닥의 나노스케일 섬모 구조를 이용해 매끄러운 유리 표면은 물론, 거친 나무나 바위 위도 기어오를 수 있으며, 문어의 흡착판 또한 유리잔처럼 평평한 표면과 조개껍질처럼 불규칙한 표면 모두에 강한 접착력을 발휘합니다.
이처럼 자연의 매니퓰레이션 시스템은 다양한 형상과 표면 거칠기를 지닌 실제 환경의 물체들을 유연하게 다룰 수 있는 능력을 보여줍니다. 반면, 인간이 만든 인공 매니퓰레이터는 여전히 제한된 범주의 물체에만 최적화되어 있는 것이 현실입니다.
BiRL은 이러한 한계를 극복하기 위해 자연에서 영감을 받은 멀티스케일 매니퓰레이터를 연구합니다. 마이크로·나노 스케일의 재료 개발에서 출발해, 이를 상위 로봇 구조와 심리스(seamless)하게 통합함으로써, 다양한 크기와 표면 특성을 지닌 물체를 안정적으로 다룰 수 있는 토탈 그리핑 솔루션(total gripping solution)을 제시합니다. 이를 통해 BiRL은 전자부품 조립에서부터 대형 산업 구조물 유지보수, 그리고 자연 환경 탐사에 이르기까지 폭넓은 응용이 가능한 차세대 매니퓰레이터와 그립퍼 기술을 개발하고 있습니다.
From the suction cups of octopuses and the nanoscale setae of geckos to the dexterous hands of humans, nature offers endless inspiration for designing manipulators capable of handling the physical world. Geckos can climb both smooth glass and rough stone thanks to countless nanoscale hair-like structures on their feet, while octopus suckers form strong adhesion not only on flat surfaces but also on irregular shells and rocks.
Natural manipulation systems operate across multiple scales, enabling flexible and robust interaction with diverse real-world objects that vary in shape, size, and surface roughness. In contrast, most artificial manipulators remain optimized for only a narrow set of predefined tasks or target objects.
At BiRL, we aim to overcome these limitations by developing nature-inspired multiscale manipulators. Starting from the design of materials at the micro/nano scale, we integrate them seamlessly into higher-level robotic structures to create total gripping solutions capable of adapting to objects across a wide range of sizes and textures.
Through this research, BiRL is pioneering next-generation manipulators and grippers with real-world impact — from microelectronic component assembly to large-scale industrial maintenance and environmental exploration.
Related work 1
H. Marvi, S. Song, M. Sitti, Experimental Investigation of Optimal Adhesion of Mushroomlike Elastomer
Microfibrillar Adhesives. Langmuir 31, 10119-10124 (2015)
Optimal fiber designs for the maximal pull-off force have been indispensable for increasing the attachment performance of recently introduced gecko-inspired reversible micro/nanofibrillar adhesives. There are several theoretical studies on such optimal designs; however, due to the lack of three-dimensional (3D) fabrication techniques that can fabricate such optimal designs in 3D, there have not been many experimental investigations on this challenge. In this study, we benefitted from recent advances in two-photon lithography techniques to fabricate mushroomlike polyurethane elastomer fibers with different aspect ratios of tip to stalk diameter (β) and tip wedge angles (θ) to investigate the effect of these two parameters on the pull-off force. We found similar trends to those predicted theoretically. We found that β has an impact on the slope of the force–displacement curve while both β and θ play a role in the stress distribution and crack propagation. We found that these effects are coupled and the optimal set of parameters also depends on the fiber material. This is the first experimental verification of such optimal designs proposed for mushroomlike microfibers. This experimental approach could be used to evaluate a wide range of complex microstructured adhesive designs suggested in the literature and optimize them.
Related work 2
S. Song, M. Sitti, Soft Grippers Using Micro-fibrillar Adhesives for Transfer Printing. Advanced Materials 26, 4901-4906 (2014).
The remarkable adhesion capabilities of biological geckos allow them to cling securely to a wide range of surfaces while maintaining exceptional controllability in attachment and detachment. This phenomenon has intrigued researchers, who have uncovered that the micro-scale structures of geckos' foot hairs maximize interfacial load sharing, while their precise foot movements leverage shear forces for swift and controlled release. However, translating these natural adhesion principles into a functional, pick-and-place manipulation system for handling macro-scale, three-dimensional objects remains a significant challenge. This paper introduces a novel soft, inflatable gripper that uses gecko-inspired micro-fiber adhesives fabricated on a flexible membrane to achieve strong attachment on a variety of complex and delicate 3D parts across different orientations. By incorporating membrane stretching to apply high shear forces at the contact interface, similar to the mechanism observed in biological geckos, the gripper significantly enhances adhesion control, achieving an adhesive switching ratio of approximately 204. This innovative approach not only enables reliable pick-and-place functionality but also enhances adaptability to diverse, non-planar 3D geometries, marking a step forward in bio-inspired adhesion technology for soft robotics.
Article & Video
Related work 3
S. Song, D.-M. Drotlef, C. Majidi, M. Sitti, Controllable load sharing for soft adhesive interfaces on three-dimensional surfaces.
Proceedings of the National Academy of Sciences 114, E4344-E4353 (2017).
For adhering to three-dimensional (3D) surfaces or objects, current adhesion systems are limited by a fundamental trade-off between 3D surface conformability and high adhesion strength. This limitation arises from the need for a soft, mechanically compliant interface, which enables conformability to nonflat and irregularly shaped surfaces but significantly reduces the interfacial fracture strength. In this work, we overcome this trade-off with an adhesion-based soft-gripping system that exhibits enhanced fracture strength without sacrificing conformability to nonplanar 3D surfaces. Composed of a gecko-inspired elastomeric microfibrillar adhesive membrane supported by a pressure-controlled deformable gripper body, the proposed soft-gripping system controls the bonding strength by changing its internal pressure and exploiting the mechanics of interfacial equal load sharing. The soft adhesion system can use up to ∼26% of the maximum adhesion of the fibrillar membrane, which is 14× higher than the adhering membrane without load sharing. Our proposed load-sharing method suggests a paradigm for soft adhesion-based gripping and transfer-printing systems that achieves area scaling similar to that of a natural gecko footpad.
Article & Video
Related work 4
S. Song, D.-M. Drotlef, D. Son, A. Koivikko, M. Sitti, Adaptive Self-Sealing Suction-Based Soft Robotic Gripper. Advanced Science 8, 2100641 (2021).
While suction cups prevail as common gripping tools for a wide range of real-world parts and surfaces, they often fail to seal the contact interface when engaging with irregular shapes and textured surfaces. In this work, the authors propose a suction-based soft robotic gripper where suction is created inside a self-sealing, highly conformable, and thin flat elastic membrane contacting a given part surface. Such a soft gripper can self-adapt the size of its effective suction area with respect to the applied load. The elastomeric membrane covering the edge of the soft gripper can develop an air-tight self-sealing with parts even smaller than the gripper diameter. Such gripper shows 4 times higher adhesion than the one without the membrane on various textured surfaces. The two major advantages, underactuated self-adaptability and enhanced suction performance allow the membrane-based suction mechanism to grip various three-dimensional (3D) geometries and delicate parts, such as egg, lime, apple, and even hydrogels without noticeable damage, which can have not been gripped with the previous adhesive microstructures-based and active suction-based soft grippers. The structural and material simplicity of the proposed soft gripper design can have broad use in diverse fields, such as digital manufacturing, robotic manipulation, transfer printing, and medical gripping.