Design and Analysis of a Soft Pneumatic Actuator with Origami Shell Reinforcement (original) (raw)
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Origami-Inspired Soft Pneumatic Actuators: Generalization and Design Optimization
Actuators
Soft actuators are essential to soft robots and can also be used with rigid-bodied robots. This paper is focused on methods for improving the applicability of origami-inspired soft pneumatic actuators (OSPA). Our method for rapidly fabricating OSPA is shown to be capable of making a range of actuator sizes out of different materials. The largest OSPA has a force-to-weight ratio of 124, and can lift a 44 kg mass using a −85 kPa supply pressure. Experiments with a smaller OSPA demonstrate that it can perform 150,000 contraction/extension cycles while carrying a 2 kg mass with minimal degradation due to its materials and design. Compared to other OSPAs for which fatigue tests were reported, our accordion pattern OSPA has the best values of work-to-mass ratio, max. force, and fatigue life. A computationally efficient FEA-based constrained optimization method for maximizing an OSPA’s work output is then proposed. A 55% improvement in the work output was predicted, while validation experi...
3D Shrinking for Rapid Fabrication of Origami-Inspired Semi-Soft Pneumatic Actuators
IEEE Access
Soft actuators are an essential component of soft robots. They are also well suited for human-friendly robots due to their intrinsic safety. The advantages of origami structures have motivated the development of origami-inspired semi-soft actuators. In this paper, a novel rapid, systematic and cost-effective fabrication method for durable origami-inspired semi-soft pneumatic actuators is presented. The proposed method employs heat-shrinkable polymers conforming to reusable molds. It is applicable to a variety of origami patterns, and it produces actuators with consistent performance. Two origami semi-soft pneumatic actuator designs (accordion and Yoshimura patterns) have been fabricated. Each actuator was fabricated in less than 10 minutes (not including the time required to create the molds and plastic components). A nonlinear finite-element model is developed to predict the actuator's folding behavior and blocked force. The results show that it can predict the blocked force with a maximum error of 5.7% relative to experimental measurements. This model can be used to improve the design of future actuators. Experimental results for isometric, isobaric, isotonic and cyclic fatigue tests for the accordion pattern actuator are included and discussed. The actuator prototype has a maximum stroke of 40 mm (or 36% of its effective length) and a maximum blocked force of 124 N at a vacuum pressure of −80 kPa. It also showed no decrease in performance and no leakage after 1000 cycles with a payload of 0.9 kg, demonstrating its durability compared to previous origami-inspired semi-soft pneumatic actuators. Finally, it has a high force-to-weight ratio as it can lift a load more than 118 times its own weight. Its performance demonstrates that powerful, lightweight and durable actuators can be easily produced by the proposed fabrication method. INDEX TERMS Origami pneumatic actuators, soft robots, pneumatic actuators, artificial muscles.
In this study, three different soft pneumatic actuators (SPA) are designed and directly fabricated through additive manufacturing using thermoplastic polyurethane (TPU) filaments. The equal total inner volume size is used in the three varied designs to compare their effect on the bending response. A material model is selected and implemented according to the uniaxial tensile test parameters. The experimental results obtained from three different soft pneumatic actuators are compared with numerical model results. Especially, the experimentally measured bending forces are compared with the numerical model counterparts. The highest continuous bending deformation is determined among the three different soft pneumatic actua-tors. Additionally, a new integrated design and manufacturing approach is presented aiming to maximize the potential bending capability of the actuator through additive manufacturing.
3D/4D-printed bending-type soft pneumatic actuators: fabrication, modelling, and control
Virtual and Physical Prototyping
This article reviews soft pneumatic actuators (SPAs) that are manufactured entirely via additive manufacturing methods. These actuators are known as four-dimensional (4D)-printed SPAs and can generate bending motions in response to either pressurised or vacuum (negative pressure) air stimulus after fabrication. They are characterised by geometrical and material factors that determine their motion trajectory, and the force they exert on manipulated soft objects in delicate applications such as food handling and non-invasive surgery. Here, we review various 3D printers and materials used for the fabrication of the pressurised air bending-type SPAs. The reported approaches for modelling and control of these actuators are presented and compared. General discussions, as well as future directions and challenges of these actuators, are given.
Computational and Experimental Design Exploration of 3D-Printed Soft Pneumatic Actuators
Advanced Intelligent Systems, 2020
Soft robotics are known for their unique advantages over conventional rigid robotics, which include safer human-machine interaction, delicate handling of fragile items, and greater durability. Soft robotic actuators are essential components in soft robots as they produce the organic motions that rigid robotic actuators have difficulty in mimicking. Pneumatic actuators (PAs) are a type of soft robotic actuator that utilizes pneumatic pressure for actuation and are commonly used; however, the relationship between their design and actuation performance is not well understood. Herein, a cubic kernelized support vector regression (SVR) model based on finite element analysis is used to explore the design space of bending PAs with respect to their bending angles through the investigation of the dependencies between different design parameters. The model obtained from the SVR is then tested by experimentally comparing the bending angle of different 3D-printed PAs from within the design space. The bending torque, an indicator of the actuation force of the PA, is also measured and compared for different design configurations. This study provides a computational and experimental framework and paves the way for future work on PAs, which has the potential to greatly propel the advancement of soft robotics.
A Systematic Overview of Soft Actuators for Robotics
In this systematic survey, an overview of non-conventional and soft-actuators is presented. The review is performed by using well-defined performance criteria with a direction to identify the exemplary applications in robotics. In addition to this, initial guidelines to measure the performance and applicability of soft actuators are provided. The meta-analysis is restricted to four main types of soft actuators: shape memory alloys (SMA), fluidic elastomer actuators (FEA), dielectric electro-activated polymers (DEAP) and shape morphing polymers (SMP). In exploring and comparing the capabilities of these actuators, the focus was on seven different aspects: compliance, topology, scalability-complexity, energy efficiency, operation range, performance and technological readiness level. The overview presented here provides a state-of-the-art summary of the advancements and can help researchers to select the most convenient soft actuators using the comprehensive comparison of the performan...
Elastomeric Origami: Programmable Paper-Elastomer Composites as Pneumatic Actuators
Advanced Functional Materials, 2012
This paper describes the development of soft pneumatic actuators based on composites consisting of elastomers with embedded sheet or fiber structures (e.g., paper or fabric) that are flexible but not extensible. On pneumatic inflation, these actuators move anisotropically, based on the motions accessible by their composite structures. They are inexpensive, simple to fabricate, light in weight, and easy to actuate. This class of structure is versatile: the same principles of design lead to actuators that respond to pressurization with a wide range of motions (bending, extension, contraction, twisting, and others). Paper, when used to introduce anisotropy into elastomers, can be readily folded into three-dimensional structures following the principles of origami; these folded structures increase the stiffness and anisotropy of the elastomeric actuators, while keeping them light in weight. These soft actuators can manipulate objects with moderate performance (for example, they can lift loads up to 120 times their weight). They can also be combined with other (for example, electrical) components to increase their functionality.
Soft Pneumatic Actuator Fascicles for High Force and Reliability
Soft Robotics, 2017
Soft pneumatic actuators (SPAs) are found in mobile robots, assistive wearable devices, and rehabilitative technologies. While soft actuators have been one of the most crucial elements of technology leading the development of the soft robotics field, they fall short of force output and bandwidth requirements for many tasks. In addition, other general problems remain open, including robustness, controllability, and repeatability. The SPA-pack architecture presented here aims to satisfy these standards of reliability crucial to the field of soft robotics, while also improving the basic performance capabilities of SPAs by borrowing advantages leveraged ubiquitously in biology; namely, the structured parallel arrangement of lower power actuators to form the basis of a larger and more powerful actuator module. An SPA-pack module consisting of a number of smaller SPAs will be studied using an analytical model and physical prototype. Experimental measurements show an SPA pack to generate over 112 N linear force, while the model indicates the benefit of parallel actuator grouping over a geometrically equivalent single SPA scale as an increasing function of the number of individual actuators in the group. For a module of four actuators, a 23% increase in force production over a volumetrically equivalent single SPA is predicted and validated, while further gains appear possible up to 50%. These findings affirm the advantage of utilizing a fascicle structure for high-performance soft robotic applications over existing monolithic SPA designs. An example of high-performance soft robotic platform will be presented to demonstrate the capability of SPA-pack modules in a complete and functional system.
Soft Actuators and Robots that Are Resistant to Mechanical Damage
Advanced Functional Materials, 2013
This paper characterizes the ability of soft pneumatic actuators and robots to resist mechanical insults that would irreversibly damage or destroy hard robotic systems—systems fabricated in metals and structural polymers, and actuated mechanically—of comparable sizes. The pneumatic networks that actuate these soft machines are formed by bonding two layers of elastomeric or polymeric materials that have different moduli on application of strain by pneumatic infl ation; this difference in strain between an extensible top layer and an inextensible, strain-limiting, bottom layer causes the pneumatic network to expand anisotropically. While all the soft machines described here are, to some extent, more resistant to damage by compressive forces, blunt impacts, and severe bending than most corresponding hard systems, the composition of the strain-limiting layers confers on them very different tensile and compressive strengths.
Single-Motor Controlled Tendon-Driven Peristaltic Soft Origami Robot
Journal of Mechanisms and Robotics, 2018
Origami-based paper folding is being used in robotics community to provide stiffness and flexibility simultaneously while designing smart structures. In this paper, we propose a novel design inspired by origami pattern service robot, which transforms its shape in the axial direction and introduce peristaltic motion therein. Here, servo motor is being used for translational actuation and springs maneuver self-deployable structure when necessary. Self-deployable springs are compressed by the application of axial force as the string gets wound around the servo motor programed to rotate with a particular speed for specified time duration. Specially coated photopolymer resin structures have been used to provide external rigidity to the springs so to avoid buckling while operation. In future, this friction coated origami service robot is envisioned to be used in an unstructured environment as the scope of applications increases at the nexus of surgical robotic navigation, houses to disast...