Pneumatic Extension Actuators With Kirigami Skins

2020 ◽  
Author(s):  
Steven Iannucci ◽  
Suyi Li
Keyword(s):  
Cylindrical Tube ◽  
Deformation Pattern ◽  
New Approach ◽  
Pneumatic Actuators ◽  
Strongly Nonlinear ◽  
Out Of Plane ◽  
Elastic And Plastic Deformations ◽  
Uniform Array ◽  
Soft Actuators ◽  
Nonlinear Behaviors

Abstract Soft pneumatic actuators have found many applications in robotics and adaptive structures. Traditionally, these actuators are constructed by wrapping layers of reinforcing helical fibers around an elastomeric tube. This approach is versatile and robust, but it suffers from a critical disadvantage: cumbersome fabrication procedures. Wrapping long helical filaments around a cylindrical tube requires expensive equipment or excessive manual labor. To address this issue, we propose a new approach towards designing and constructing pneumatic actuators by exploiting the principle of kirigami, the ancient art of paper cutting. More specifically, we use “kirigami skins” — plastic sleeves with carefully arranged slit cuts — to replace the reinforcing helical fibers. This paper presents an initial investigation on a set of linear extension actuators featuring kirigami skins with a uniform array of cross-shaped, orthogonal cuts. When under internal pressurization, the rectangular-shaped facets defined by these cuts can rotate and induce the desired extension motion. Through extensive experiments, we analyze the elastic and plastic deformations of these kirigami skins alone under tension. The results show strongly nonlinear behaviors involving both in-plane facet rotation the out-of-plane buckling. Such a deformation pattern offers valuable insights into the actuator’s performance under pressure. Moreover, both the deformation characteristics and actuation performance are “programmable” by tailoring the cut geometry. This study lays down the foundation for constructing more capable Kirigami-skinned soft actuators that can achieve sophisticated motions.

scholarly journals Pneumatic Soft Actuators With Kirigami Skins

2021 ◽  
Vol 8 ◽  
Author(s):  
Hesameddin Khosravi ◽  
Steven M. Iannucci ◽  
Suyi Li
Keyword(s):  
Pattern Design ◽  
Pneumatic Actuators ◽  
Volumetric Expansion ◽  
New Family ◽  
Design Flexibility ◽  
Out Of Plane ◽  
Cutting Pattern ◽  
Motion Characteristics ◽  
Soft Actuators ◽  
Robotic Applications

Soft pneumatic actuators have become indispensable for many robotic applications due to their reliability, safety, and design flexibility. However, the currently available actuator designs can be challenging to fabricate, requiring labor-intensive and time-consuming processes like reinforcing fiber wrapping and elastomer curing. To address this issue, we propose to use simple-to-fabricate kirigami skins—plastic sleeves with carefully arranged slit cuts—to construct pneumatic actuators with pre-programmable motion capabilities. Such kirigami skin, wrapped outside a cylindrical balloon, can transform the volumetric expansion from pneumatic pressure into anisotropic stretching and shearing, creating a combination of axial extension and twisting in the actuator. Moreover, the kirigami skin exhibits out-of-plane buckling near the slit cut, which enables high stretchability. To capture such complex deformations, we formulate and experimentally validates a new kinematics model to uncover the linkage between the kirigami cutting pattern design and the actuator’s motion characteristics. This model uses a virtual fold and rigid-facet assumption to simplify the motion analysis without sacrificing accuracy. Moreover, we tested the pressure-stroke performance and elastoplastic behaviors of the kirigami-skinned actuator to establish an operation protocol for repeatable performance. Analytical and experimental parametric analysis shows that one can effectively pre-program the actuator’s motion performance, with considerable freedom, simply by adjusting the angle and length of the slit cuts. The results of this study can establish the design and analysis framework for a new family of kirigami-skinned pneumatic actuators for many robotic applications.

Valveless microliter combustion for densely packed arrays of powerful soft actuators

2021 ◽  
Vol 118 (39) ◽  
pp. e2106553118
Author(s):  
Ronald H. Heisser ◽  
Cameron A. Aubin ◽  
Ofek Peretz ◽  
Nicholas Kincaid ◽  
Hyeon Seok An ◽  
...  
Keyword(s):  
Tactile Stimulation ◽  
Exothermic Reaction ◽  
Tactile Display ◽  
Metal Electrodes ◽  
Pneumatic Actuators ◽  
Display Technology ◽  
Fluidic Actuators ◽  
Operational Frequency ◽  
Soft Actuators ◽  
Flame Behavior

Existing tactile stimulation technologies powered by small actuators offer low-resolution stimuli compared to the enormous mechanoreceptor density of human skin. Arrays of soft pneumatic actuators initially show promise as small-resolution (1- to 3-mm diameter), highly conformable tactile display strategies yet ultimately fail because of their need for valves bulkier than the actuators themselves. In this paper, we demonstrate an array of individually addressable, soft fluidic actuators that operate without electromechanical valves. We achieve this by using microscale combustion and localized thermal flame quenching. Precisely, liquid metal electrodes produce sparks to ignite fuel lean methane–oxygen mixtures in a 5-mm diameter, 2-mm tall silicone cylinder. The exothermic reaction quickly pressurizes the cylinder, displacing a silicone membrane up to 6 mm in under 1 ms. This device has an estimated free-inflation instantaneous stroke power of 3 W. The maximum reported operational frequency of these cylinders is 1.2 kHz with average displacements of ∼100 µm. We demonstrate that, at these small scales, the wall-quenching flame behavior also allows operation of a 3 × 3 array of 3-mm diameter cylinders with 4-mm pitch. Though we primarily present our device as a tactile display technology, it is a platform microactuator technology with application beyond this one.

Evaluation of a Suitable Material for Soft Actuator Through Experiments and FE Simulations

2022 ◽  
pp. 339-353
Author(s):  
Elango Natarajan ◽  
Muhammad Rusydi Muhammad Razif ◽  
AAM Faudzi ◽  
Palanikumar K.
Keyword(s):  
Tensile Modulus ◽  
Cylindrical Tube ◽  
Fast Response ◽  
Nonlinear Material ◽  
Element Analysis ◽  
Elongation At Break ◽  
Multi Wall Carbon Nanotubes ◽  
Suitable Material ◽  
The Finite Element Analysis ◽  
Soft Actuators

Soft actuators are generally built to achieve extension, contraction, curling, or bending motions needed for robotic or medical applications. It is prepared with a cylindrical tube, braided with fibers that restrict the radial motion and produce the extension, contraction, or bending. The actuation is achieved through the input of compressed air with a different pressure. The stiffness of the materials controls the magnitude of the actuation. In the present study, Silastic-P1 silicone RTV and multi-wall carbon nanotubes (MWCNT) with reinforced silicone are considered for the evaluation. The dumbbell samples are prepared from both materials as per ASTM D412-06a (ISO 37) standard and their corresponding tensile strength, elongation at break, and tensile modulus are measured. The Ogden nonlinear material constants of respective materials are estimated and used further in the finite element analysis of extension, contraction, and bending soft actuators. It is observed that silicone RTV is better in high strain and fast response, whereas, silicone/MWCNT is better at achieving high actuation.

A soft ring oscillator

2019 ◽  
Vol 4 (31) ◽  
pp. eaaw5496 ◽  
Author(s):  
Daniel J. Preston ◽  
Haihui Joy Jiang ◽  
Vanessa Sanchez ◽  
Philipp Rothemund ◽  
Jeff Rawson ◽  
...  
Keyword(s):  
Constant Pressure ◽  
Particle Separation ◽  
Schmitt Trigger ◽  
Ring Oscillator ◽  
System Level ◽  
Pressure Source ◽  
Pneumatic Actuators ◽  
System Parameters ◽  
Soft Actuators ◽  
Single Constant

Periodic actuation of multiple soft, pneumatic actuators requires coordinated function of multiple, separate components. This work demonstrates a soft, pneumatic ring oscillator that induces temporally coordinated periodic motion in soft actuators using a single, constant-pressure source, without hard valves or electronic controls. The fundamental unit of this ring oscillator is a soft, pneumatic inverter (an inverting Schmitt trigger) that switches between its two states (“on” and “off”) using two instabilities in elastomeric structures: buckling of internal tubing and snap-through of a hemispherical membrane. An odd number of these inverters connected in a loop produces the same number of periodically oscillating outputs, resulting from a third, system-level instability; the frequency of oscillation depends on three system parameters that can be adjusted. These oscillatory output pressures enable several applications, including undulating and rolling motions in soft robots, size-based particle separation, pneumatic mechanotherapy, and metering of fluids. The soft ring oscillator eliminates the need for hard valves and electronic controls in these applications.

Torsional Stiffness Improvement of a Soft Pneumatic Finger Using Embedded Skeleton

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Amin Lotfiani ◽  
Huichan Zhao ◽  
Zhufeng Shao ◽  
Xili Yi
Keyword(s):  
Torsional Stiffness ◽  
Good Precision ◽  
Pneumatic Actuators ◽  
Finite Element Approach ◽  
Grasping And Manipulation ◽  
Element Approach ◽  
Series Of Experiments ◽  
Soft Actuators ◽  
Compact Design ◽  
Rigid Skeleton

Abstract Silicone-based pneumatic actuators are among the most widely used soft actuators in adaptable fingers. However, due to the soft nature of silicone, the performance of these fingers is highly affected by the low torsional stiffness, which may cause failure in grasping and manipulation. To address this problem, a compact design is proposed by embedding a rigid skeleton into a soft pneumatic finger. A finite element approach with an analysical model is used to evaluate the performance of the fingers both with and without the skeleton. Then, a series of experiments is performed to study the bending motion and rigidity of the fingers. The results reveal that the skeleton increases the torsional stiffness of the finger up to 300%. Furthermore, the consistency with the experimental data indicates the good precision of the proposed modeling method. Finally, a two-finger hand is designed to evaluate the performance of the reinforced finger in reality. The grasp experiments illustrate that the hybrid finger with the skeleton is highly adaptable and can successfully grasp and manipulate heavy objects. Thus, a potential approach is proposed to improve the torsional stiffness of silicone-based pneumatic fingers while maintaining adaptability.

Evaluation of a Suitable Material for Soft Actuator Through Experiments and FE Simulations

2020 ◽  
Vol 10 (2) ◽  
pp. 64-76
Author(s):  
Elango Natarajan ◽  
Muhammad Rusydi Muhammad Razif ◽  
AAM Faudzi ◽  
Palanikumar K.
Keyword(s):  
Tensile Modulus ◽  
Cylindrical Tube ◽  
Fast Response ◽  
Nonlinear Material ◽  
Element Analysis ◽  
Elongation At Break ◽  
Multi Wall Carbon Nanotubes ◽  
Suitable Material ◽  
The Finite Element Analysis ◽  
Soft Actuators

Soft actuators are generally built to achieve extension, contraction, curling, or bending motions needed for robotic or medical applications. It is prepared with a cylindrical tube, braided with fibers that restrict the radial motion and produce the extension, contraction, or bending. The actuation is achieved through the input of compressed air with a different pressure. The stiffness of the materials controls the magnitude of the actuation. In the present study, Silastic-P1 silicone RTV and multi-wall carbon nanotubes (MWCNT) with reinforced silicone are considered for the evaluation. The dumbbell samples are prepared from both materials as per ASTM D412-06a (ISO 37) standard and their corresponding tensile strength, elongation at break, and tensile modulus are measured. The Ogden nonlinear material constants of respective materials are estimated and used further in the finite element analysis of extension, contraction, and bending soft actuators. It is observed that silicone RTV is better in high strain and fast response, whereas, silicone/MWCNT is better at achieving high actuation.

scholarly journals Rapid Design and Analysis of Microtube Pneumatic Actuators Using Line-Segment and Multi-Segment Euler–Bernoulli Beam Models

Micromachines ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 780 ◽  
Author(s):  
Myunggi Ji ◽  
Qiang Li ◽  
In Ho Cho ◽  
Jaeyoun Kim
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Line Segment ◽  
Beam Model ◽  
Element Analysis ◽  
Pneumatic Actuators ◽  
Design And Optimization ◽  
Rapid Design ◽  
The Finite Element Analysis ◽  
Soft Actuators

Soft material-based pneumatic microtube actuators are attracting intense interest, since their bending motion is potentially useful for the safe manipulation of delicate biological objects. To increase their utility in biomedicine, researchers have begun to apply shape-engineering to the microtubes to diversify their bending patterns. However, design and analysis of such microtube actuators are challenging in general, due to their continuum natures and small dimensions. In this paper, we establish two methods for rapid design, analysis, and optimization of such complex, shape-engineered microtube actuators that are based on the line-segment model and the multi-segment Euler–Bernoulli’s beam model, respectively, and are less computation-intensive than the more conventional method based on finite element analysis. To validate the models, we first realized multi-segment microtube actuators physically, then compared their experimentally observed motions against those obtained from the models. We obtained good agreements between the three sets of results with their maximum bending-angle errors falling within ±11%. In terms of computational efficiency, our models decreased the simulation time significantly, down to a few seconds, in contrast with the finite element analysis that sometimes can take hours. The models reported in this paper exhibit great potential for rapid and facile design and optimization of shape-engineered soft actuators.

Study on Welding Deformations of Shipboard of Container Vessel

2011 ◽  
Vol 488-489 ◽  
pp. 218-221
Author(s):  
Hong Li ◽  
Da Lu Qiu ◽  
Guang Lei Li ◽  
Hui Long Ren
Keyword(s):  
Heat Flux ◽  
Heat Source ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Transient Temperature ◽  
Plastic Strains ◽  
Out Of Plane ◽  
Inherent Strain ◽  
Nonlinear Behaviors ◽  
Plane Deformations

Residual plastic strains of the shipboard are the product of nonlinear behaviors during welding. Deformations of a welded shipboard injure the beauty of appearance of the ship, cause errors during the assembly of the shipboard and reduce the strength of the ship. Residual welding deformations of shipboard of a container vessel are studied in this paper. Nonlinear three dimensional transient temperature fields are analyzed by FEM first. The heat source is modeled as a moving heat flux following a Gaussian distribution. Then, applying the equivalent loads induced by the inherent strain on the shipboard, the final in-plane shrinkage and out-of-plane deformations are calculated. Being compared with the experimental results of deformations, the simulated results show mostly conformity.

A General Solution for the Pressurized Elastoplastic Tube

1992 ◽  
Vol 59 (1) ◽  
pp. 20-26 ◽  
Author(s):  
David Durban ◽  
Michael Kubi
Keyword(s):  
General Solution ◽  
Finite Strain ◽  
Cylindrical Tube ◽  
Yield Function ◽  
Material Behavior ◽  
Deformation Pattern ◽  
Perfectly Plastic ◽  
Plastic Phase ◽  
Thin Walled ◽  
Elastic Perfectly Plastic

The problem of a thick-walled cylindrical tube subjected to internal pressure is investigated within the framework of continuum plasticity. Material behavior is modeled by a finite strain elastoplastic flow theory based on the Tresca yield function. The deformation pattern is restricted by the plane-strain condition but arbitrary hardening and elastic compressibility are accounted for. A general solution is given in terms of quadratures. The analysis also includes treatment of a second plastic phase, characterized by corner relations, that may develop at the inner boundary. It is shown that the interface between the two plastic regions moves initially outwards and then, beyond a certain strain level, it moves back inwards. Some useful and simple results are given for thin-walled tubes of hardening materials and for thick-walled elastic/perfectly plastic tubes.

Development of Miniaturized Rubber Muscle Actuator Driven by Gas-Liquid Phase Change

2016 ◽  
Author(s):  
Tomonori Kato ◽  
Kazuki Sakuragi ◽  
Mingzhao Cheng ◽  
Ryo Kakiyama ◽  
Yuta Matsunaga ◽  
...  
Keyword(s):  
Control System ◽  
Liquid Phase ◽  
Frequency Response ◽  
Artificial Muscle ◽  
Phase Changes ◽  
Corner Frequency ◽  
Pi Control ◽  
Pneumatic Actuators ◽  
Frequency Responses ◽  
Soft Actuators

The goal of this study is to develop a miniaturized artificial muscle in which a tiny compressor can be installed. Pneumatic actuators, such as pneumatic artificial rubber muscles (PARMs), have been widely used in many industrial and robotic research applications because they are compact and lightweight. However, the compressors driving such actuators are relatively large. To solve this problem, the authors have been researching soft actuators driven by gas-liquid phase changes (GLPCs). In this study, a fixed chamber containing a constantan heater and fluorocarbon was used to generate pressure instead of a compressor. The pressure generation caused by the GLPC was confirmed, and a PARM contraction experiment was then conducted. Additionally, a PI control system was built to test the step and frequency responses of the actuator. A frequency response of up to 4.0 Hz was determined, and the corner frequency was found to be approximately 1.5 Hz. The size of the actuator was reduced by removing the chamber and installing the heater in the rubber muscle. A PARM driving experiment was conducted, and the performance of the PARM was evaluated. The miniaturized actuator consumes less power than the original actuator.

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