Puffer: Pop-Up Flat Folding Explorer Robot

A repeatably reconfigurable robot, comprising at least two printed circuit board (PCB) rigid sections, at least one PCB flexible section coupled to the at least two PCB rigid sections, at least one wheel, hybrid wheel propeller, wheel and propeller, or hybrid wheel screw propeller rotatably coupled to at least one of the at least two PCB rigid sections and at least one actuator coupled to the at least two PCB rigid sections, wherein the at least one actuator folds and unfolds the repeatably reconfigurable robot

모듈화 기반의 유연 소자 조립 방법 및 전자 피부 기술

학위논문(박사) -- 서울대학교대학원 : 공과대학 전기·정보공학부, 2023. 2. 홍용택.일반적인 전자소자는 단단한 폼팩터로 인해 피부에 부착하여 활용하기에 쉽지 않다는 단점이 있다. 또한 외부의 충격으로 인해 기기가 쉽게 부서질 수 있다. 최근에는 이런 문제들을 해결하기 위해, 전자 소자 및 기기에 유연함을 부여하는 기술 개발이 활발히 이루어지고 있다. 먼저, 구부리거나 늘릴 수 있는 소프트 센서가 개발되었으며, 그에 따라서 사람의 피부에 센서 패치를 부착하고 사람의 맥박, 심전도 (ECG) 또는 근전도 (EMG)와 같은 생체 활성 신호를 보다 정확히 측정할 수 있게 되었다. 또한 이러한 센서 소자 다수를 유연 기판 위에 전기적으로 연결할 수 있는 유연 전극 제작 기술이 개발되었고, 덕분에 다기능의 통합된 센서 패치도 개발할 수 있었다. 최근의 유연 전자 소자나 기기도 현재 널리 사용되는 IC 칩으로 구성된 전기 회로를 활용하여 고성능의 데이터 처리를 수행하거나 빠른 속도로 데이터 전송을 할 수 있게 되었다. 이러한 기술이 가능한 이유는 FHE (flexible hybrid electronics) 또는 SHE (stretchable hybrid electronics) 기술의 발전 덕분이다. 이러한 하이브리드형 전자 소자 및 기기는 인쇄 기술로 제작된 유연 센서와 같은 구성 요소를 유연 전극을 통해 기존의 단단한 PCB 회로나 유연한 PCB 회로에 연결하는 기술로서, 기존의 고성능의 데이터 처리 능력과 유연 센서의 높은 민감도라는 두 장점을 모두 활용할 수 있는 장점이 있다. 본 논문에서는 SHE를 활용한 유연 모듈화 기반의 유연 전자 소자 조립 방법에 대해서 연구하였다. 시스템 수준의 유연 센서 통합 기기를 개발하기 앞서 개별 유연 센서 기술에 대한 연구를 진행하였다. 고민감도 유연 압력 센서를 기반으로 하는 두 가지 유형의 유연 센서를 제작하였고, 그 센서들의 특성을 조사하였다. 한 가지는 유연 3축 힘 센서이며, 다른 한가지는 신축에 영향을 받지 않는 압력 센서이다. 이러한 개별 센서 기술을 가상현실(VR)이나 증강현실(AR)에서 새로운 형태의 컨트롤러로 사용할 수 있는 유저 인터페이스 기술을 제시하였다. 또한 인체의 변형과 피부의 신축에 의해서도 민감도의 변화가 거의 없이 맥박을 읽어 들일 수 있는 센서도 제시하였다. 유연 센서의 신호 변화 범위에 맞는 Read-out회로를 설계하여 이를 위의 기술에 적용하였다. 본 논문에서는 개별 센서 및 회로에 대한 연구를 기반으로 위의 개별 요소들을 모듈화 기반의 유연 블록으로 탈바꿈하였다. SHE 기술의 Island-bridge 기술을 기반으로 센서, 데이터 처리 회로 등 기기 성능에 중심 역할을 하는 핵심 요소들을 단단한 열가소성 필름 상에 인쇄 및 제작하였다. 또한, 열가소성 필름과 유연 기판 사이에 중간층을 삽입하여 더 높은 변형에서도 유지되는 유연 모듈화 전자 블록을 개발하였다. 센서 블록, 회로 블록, 인터커텍트 블록으로 구성된 모듈화 블록들을 피부 위에서 빠르게 조립함으로써, 사용자마다 다른 신체 사이즈와 비율에 맞춤형으로 제작되는 웨어러블 기기를 완성할 수 있다. 기존의 고정된 설계로 제작되는 유연 전자소자는 사람마다 다른 신체 요인을 고려하지 않고 유일한 설계로 제작되기 대문에, 센서 정렬 오류와 같은 문제가 발생하고 신호를 읽는 데 정확도가 떨어지는 문제가 생길 수 있다. 위의 모듈화 블록 조립 방법은 한번 조립된 후, 분해될 수 없는 단점을 가지고 있다. 우리는 점착성을 갖고 높은 전도성 역시 갖는 접촉 패드 기술을 개발하여 위 기술을 개선하였다. 점착성 전도 패드는 PEIE와 PDMS, 그리고 자기 수직 정렬된 은 코팅 니켈 (AgNi) 입자의 혼합물이다. 이러한 패드가 형성된 FPCB를 유연 모듈화 전자 블록으로 사용하였고, 이 기술을 신축성을 갖는 인터커넥트 블록으로 연결하여 유연 기기를 완성할 수 있다. 이 기술은 조립과 동시에 기기가 완성되는 장점이 있어, 자라나는 소프트 로봇 바디에 맞게 자라나는 로봇 피부로서 활용이 가능하다. 본 논문에서는 우리의 기술이 미래에 웨어러블 기기나 피부 부착 가능한 기기에 적용될 수 있고, 그것들의 핵심 기술로 활용될 가능성을 확인하였다. 또한 전자 피부나 유연 로봇 피부로의 활용도도 제시하였다.General electronic devices feature rigid form factors, mismatching with the form factor of human skin, and vulnerability to deformation of the devices. Recently, in order to close this gap, techniques for imparting softness to electronics and devices have become considerably advanced. Soft sensors have been developed that can be bent or stretched; thus, they can be patched on human skin and measure bioactive signals such as human pulse, electrocardiography (ECG), or electromyography (EMG). In addition, soft interconnect manufacturing technology that can electrically connect these skin-attached sensor devices has been developed, and an integrated multi-functional sensor deceives also emerged. Soft electronics can also realize high-performance computing or data transmission by employing electric circuits using mature IC chips. Flexible hybrid electronics (FHE) and stretchable hybrid electronics (SHE) technologies have made these technologies possible. Hybrid-type electronics can be manufactured by connecting components such as printed soft sensors to rigid or soft circuits through soft interconnects. In this dissertation, we describe the assembly of soft modular electronic blocks using SHE. In addition, we have been conducting a study on individual soft sensor technology to develop a system-level soft sensor-integrated system. Based on a highly sensitive soft pressure sensor, two types of soft sensors were fabricated, and their characteristics are investigated: 1) Soft 3-axis force sensor and 2) stretching-insensitive pressure sensor. The applicability of these individual sensor technologies to a user interface that can be used as a controller of novel types of virtual reality (VR) or augmented reality (AR) was confirmed. In addition, we demonstrated a sensor device that can read a pulse signal with a slight decrease in sensitivity even under human body deformation. Our soft sensor read-out circuits suitable for the specification or our sensor enable the above applications to be implemented. Based on the study of individual sensors and circuits, we conduct transforms of these individual elements into modularized blocks. The island-bridge technique of SHE technology was used, and key components that play a significant role in device performance, such as sensors and computation circuits, were printed on thermoplastic film. In addition, strain-engineered soft modular blocks were developed by inserting a strain-relief layer, an interlayer, between the thermoplastic film and the elastomeric substrate. Through our rapid on-skin soft modular electronic blocks (SMEBs) assembly of soft modular blocks of sensor blocks, circuit blocks, and interconnect blocks, we can create soft wearable flexion monitoring tailored to users with various body proportions and sizes. Because soft electronic devices with a fixed design are manufactured in a single design without considering the body factors that differ from person to person, issues such as sensor misalignment may occur, and signal acquisition accuracy may be degraded. Soft modular blocks above have limitations that can be disassembled. Through the development of sticky and highly conductive contact pad technology, we have made progress in SMEBs technology. The sticky contact pad is fabricated by using a composite of polyethylenimine ethoxylated (PEIE) and polydimethylsiloxane (PDMS) as a sticky matrix and introducing vertically aligned silver-coated nickel (AgNi) particles inside the matrix during the curing process. The flexible printed circuit board (FPCB) on which the sticky contact pad is formed is used as a soft modular block. Soft devices can be made by electrically connecting those blocks via stretchable interconnect blocks. Utilizing this technology makes it possible to implement robotic skin technology to actuate soft robotics. Thanks to its reconfigurable feature, it can also be applied to a growing soft robot body. It can also be achieved by simply assembling interconnect blocks to new heater blocks without additional treatment. We demonstrated that our technologies could be utilized and be one of the key technologies for future wearable or skin-attachable applications. We also confirmed the feasibility of application to electronic skins or soft robotic skins.Chapter 1. Introduction 1 1.1 Soft Electronics 1 1.2 Flexible/ Stretchable Hybrid Electronics 5 1.3 Modularized Electronic Blocks Assembly 8 1.4 Organization of this dissertation 10 Reference 12 Chapter 2. Soft pressure/3-axis sensors and their potential applications 15 2.1 Soft 3-Axis Force Sensors 15 2.1.1 Introduction 15 2.1.2 Results and Discussions 19 2.1.3 Potential Applications 25 2.1.4 Experimental Section 31 2.2 Stretching-insensitive Pressure Sensor 33 2.2.1 Introduction 33 2.2.2 Results and Discussions 36 2.2.3 Potential Application 43 2.2.4 Experimental Section 46 Chapter 3. Soft Modular Electronic Blocks (SMEBs) 50 3.1 Introduction 50 3.2 Soft Modular electronic blocks (SMEBs) 53 3.3 Mechanical and Electrical Stability of SMEBs 60 3.4 Application : Tailored Wearable Systems 68 3.5 Experimental section 79 Chapter 4. Reconfigurable and Reusable Soft Modular Electronic Blocks 90 4.1 Introduction 90 4.2 Reconfigurable and Reusable Soft Modular Electronic Blocks 93 4.3 Sticky Contact Pad Characteristics 97 4.4 Application: Electronic Skins 106 4.5 Experimental section 120 Chapter 5. Conclusion 127 Abstract in Korean 129박

A kirigami approach for controlling mechanical and sensing properties of films

Tuning the layout of elasticity in materials opens new opportunities to add various functionalities into a system, ranging from load-enduring capacity and shape-morphing capability in aeronautics to self-foldability and controlled diffusion rates in drug delivery applications. Recently, the Japanese art of paper cutting technique called kirigami has positioned itself as a simple yet powerful strategy to program unique functionalities into intrinsically inextensible, stiff materials without adjusting chemical compositions, including elastic softening, creation of complex 3D structures, and extreme stretchability. Thus, various applications have been realized by utilizing the kirigami principle. These applications include wearable electronics, sensors, stretchable lithium batteries, solar trackers, and reconfigurable structures. However, coupling the primary geometric deformation modes (i.e., bending and rotation) in kirigami films to control mechanical response as well as electronic properties (e.g., shift in resonant frequency) have been limited. In this thesis, we present a strategy where the inclusion of carefully designed cuts allows for fine tuning of mechanical and electronic properties of materials. Starting from fundamentals of kirigami mechanics, we show that stiffness tunability and deformability of kirigami structures are signicantly infuenced by the addition of minor cuts adjacent to major cuts. The dimension and position of minor cuts relative to major cuts determines geometric deformation modes between bending of beams and hinge rotations, which results in high tunability of mechanical properties. The experimental results are validated by beam mechanics with different boundary conditions (Chapter 2). The sensors for human activity monitoring and soft robotic systems require considerable extents of deformation. Furthermore, reducing or eliminating wiring components allows for more compliant and less complex systems by excluding semirigid wiring or connection points. We create a kirigami-inspired passive resonant sensor where the deformation normal to the planar surface changes the capacitance, inductance, and resonant frequency. This study demonstrates that the device allows for accurate measurements of large deformations (\u3e 10X sensor thickness) in both air and water media (Chapter 3)

Design of Soft, Modular Appendages for a Bio-inspired Multi-Legged Terrestrial Robot

Soft robots have the ability to adapt to their environment, which makes them suitable for use in disaster areas and agricultural fields, where their mobility is constrained by complex terrain. One of the main challenges in developing soft terrestrial robots is that the robot must be soft enough to adapt to its environment, but also rigid enough to exert the required force on the ground to locomote. In this paper, we report a pneumatically driven, soft modular appendage made of silicone for a terrestrial robot capable of generating specific mechanical movement to locomote and transport loads in the desired direction. This two-segmented soft appendage uses actuation in between the joint and the lower segment of the appendage to ensure adequate rigidity to exert the required force to locomote. A prototype of a soft-rigid-bodied tethered physical robot was developed and two sets of experiments were carried out in both air and underwater environments to assess its performance. The experimental results address the effectiveness of the soft appendage to generate adequate force to navigate through various environments and our design method offers a simple, low-cost, and efficient way to develop terradynamically capable soft appendages that can be used in a variety of locomotion applications

Origami-inspired kinematic morphing surfaces

In the past decades, an emerging technology has tried to build robots from soft materials to mimic living organisms in nature. Despite the flexibility and adaptability offered by such robots, the soft materials introduce very high or even infinite degrees of freedom (DoFs). It is thus challenging to achieve controllable shape changes on soft materials, which are essential for robots to carry out their functions. Many material-based approaches have been attempted to constrain the excessive DoFs of soft materials, so that they can bend, stretch, or twist as desired. In most applications, considering that only limited mobility is required to perform certain tasks, it would also be feasible to employ mechanical coupling to remove unwanted motions. To achieve this, engineers resort to origami techniques to design predictable and controllable robotic structures. However, most origami-inspired robots are built from existing patterns, where the material thickness is always neglected. Using zero-thickness sheets restricts the modelling accuracy, fabrication flexibility, and motion possibility. A recent study reveals that considering material thickness can further reduce the overall DoFs of origami, since its mechanical model is often overconstrained and differs significantly from that of the zero-thickness one. The novel structures with thickness, known as thick-panel origami, were originally developed for space use and are not accessible to roboticists. Hence, a thorough investigation is needed to develop thick-panel origami targeting robotic applications. This thesis is thus centred on two aspects. The first is to systematically design thick-panel origami for shape-changing, namely morphing surfaces. The second part extends selected surfaces into the design of intelligent robots, with the aim of simplified design, actuation, and control. The main achievements of this research are as follows. Firstly, a systematic design methodology is proposed to map thick-panel origami with 6R spatial overconstrained linkages. A library of morphing units whose thicknesses are uniform and not negligible is thus uncovered. Morphing surfaces, which are the tessellations or assemblies of morphing units, are then demonstrated to achieve common soft material behaviours, including bending, expanding, and twisting. Complex motions such as wrapping and curling are also presented. The mobility of these surfaces is restricted to one, while bifurcations may exist for extra motion possibilities. Secondly, a robotic gripper is designed from the wrapping surface. By exploiting the bifurcation and compliance of the surface, the proposed gripper has achieved a balance between motion dexterity and control complexity, aiming to solve the control challenges of grasping and manipulation. More specifically, the gripper can grasp objects of various shapes with one motor and conduct manipulations with only two control inputs, as opposed to many current end effectors that can only grasp or need around 20 actuators for manipulation tasks. On top of this, the gripper can be 3D-printed with ease, largely streamlining the mechanical design and fabrication process. Lastly, a reconfigurable robot is demonstrated on the curling surface to mimic a millipede's morphology. The robot can not only morph into a coil but also reconfigure into wave-like and triangular shapes. The reconfigurability is achieved by utilising the kinematic bifurcations of the surface without increasing the system's overall DoF. The design is also free from module disconnection and reconnection for new configurations, making the system more robust. The proof-of-concept robotic study has showcased the potential of maintaining reconfigurability with a relatively straightforward control strategy

Exploiting Multi Stability of Compliant Locking Mechanism for Reconfigurable Articulation in Robotic Arm

This study analyzes a biology inspired approach of utilizing a compliant unit actuator to simplify the control requirements for a soft robotic arm. A robot arm is constructed from a series of compliant unit actuators that precisely actuate between two stable states. The extended state can be characterized as a rigid link with a high bending stiffness. The compressed state can be characterized as a flexible joint with a low bending stiffness. Without the use of an external power source, the bistable mechanism remains in each of the stable states. The unit actuator can demonstrate pseudo-linkage kinematics that require less control parameters than entirely soft manipulators. An advantage of using compliant mechanisms to design a robotic arm is that the bending stiffness ratio between the extended and compressed states is related to the frame and flexural member geometry. Post buckling characteristics of thin flexural members, combined with a cantilever style frame design gives the unit actuator versatile advantages over existing actuator designs like layer jamming and shape memory polymers. To achieve efficient movement with the optimized unit actuator design, experimental validation was performed, and a robotic arm prototype was fabricated. The tendon-driven robotic arm consisted of three modules and proved the capability of transforming and rotating in the eight configurations. The deformations of the robotic arm are accurately predicted by the kinematic model and validate the compliant mechanism arm and simple control system