Modeling and parameter identification of thin, tightly rolled dielectric elastomer actuators

2021 ◽  
Author(s):  
Johannes Prechtl ◽  
Julian Kunze ◽  
Giacomo Moretti ◽  
Daniel Bruch ◽  
Stefan Seelecke ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Mathematical Structure ◽  
High Energy ◽  
Dielectric Elastomer ◽  
Lumped Parameter Model ◽  
High Energy Density ◽  
Dielectric Elastomer Actuators ◽  
Lumped Parameter ◽  
The Many ◽  
And Control

Abstract Due to their large deformation, high energy density, and high compliance, dielectric elastomer actuators (DEAs) have found a number of applications in several areas of mechatronics and robotics. Among the many types of DEAs proposed in the literature, rolled DEAs (RDEAs) represent one of the most popular configurations. RDEAs can be effectively used as compact muscle-like actuators for soft robots, since they allow eliminating the need for external motors or compressors while providing at the same time a flexible and lightweight structure with self-sensing capabilities. To effectively design and control complex RDEA-driven systems and robots, accurate and numerically efficient mathematical models need to be developed. In this work, we propose a novel lumped-parameter model for silicone-based, thin and tightly rolled DEAs. The model is grounded on a free-energy approach, and permits to describe the electro-mechanically coupled response of the transducer with a set of nonlinear ordinary differential equations. After deriving the constitutive relationships, the model is validated by means of an extensive experimental campaign, conducted on three RDEA specimens having different geometries. It is shown how the developed model permits to accurately predict the effects of several parameters (external load, applied voltage, actuator geometry) on the RDEA electro-mechanical response, while maintaining an overall simple mathematical structure.

scholarly journals Soft, tough, and fast polyacrylate dielectric elastomer for non-magnetic motor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Li-Juan Yin ◽  
Yu Zhao ◽  
Jing Zhu ◽  
Minhao Yang ◽  
Huichan Zhao ◽  
...  
Keyword(s):  
High Performance ◽  
Crosslinking Agent ◽  
High Energy ◽  
Dielectric Elastomer ◽  
High Energy Density ◽  
Dielectric Elastomers ◽  
Dielectric Elastomer Actuators ◽  
Response Bandwidth ◽  
Electrically Actuated ◽  
Soft Actuators

AbstractDielectric elastomer actuators (DEAs) with large electrically-actuated strain can build light-weight and flexible non-magnetic motors. However, dielectric elastomers commonly used in the field of soft actuation suffer from high stiffness, low strength, and high driving field, severely limiting the DEA’s actuating performance. Here we design a new polyacrylate dielectric elastomer with optimized crosslinking network by rationally employing the difunctional macromolecular crosslinking agent. The proposed elastomer simultaneously possesses desirable modulus (~0.073 MPa), high toughness (elongation ~2400%), low mechanical loss (tan δm = 0.21@1 Hz, 20 °C), and satisfactory dielectric properties ($${\varepsilon }_{{{{{{\rm{r}}}}}}}$$ ε r  = 5.75, tan δe = 0.0019 @1 kHz), and accordingly, large actuation strain (118% @ 70 MV m−1), high energy density (0.24 MJ m−3 @ 70 MV m−1), and rapid response (bandwidth above 100 Hz). Compared with VHBTM 4910, the non-magnetic motor made of our elastomer presents 15 times higher rotation speed. These findings offer a strategy to fabricate high-performance dielectric elastomers for soft actuators.

scholarly journals Design, Manufacturing, and Characterization of Thin, Core-Free, Rolled Dielectric Elastomer Actuators

Actuators ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 69
Author(s):  
Julian Kunze ◽  
Johannes Prechtl ◽  
Daniel Bruch ◽  
Bettina Fasolt ◽  
Sophie Nalbach ◽  
...  
Keyword(s):  
Energy Density ◽  
High Energy ◽  
Dielectric Elastomer ◽  
High Energy Density ◽  
Artificial Muscles ◽  
Hollow Core ◽  
Dielectric Elastomer Actuators ◽  
Mass Load ◽  
Silicone Film

In this work, we develop a coreless rolled dielectric elastomer actuator (CORDEA) to be used as artificial muscles in soft robotic structures. The new CORDEA concept is based on a 50 µm silicone film with screen-printed electrodes made of carbon black suspended in polydimethylsiloxane. Two printed silicone films are stacked together and then tightly rolled in a spiral-like structure. Readily available off-the-shelf components are used to implement both electrical and mechanical contacts. A novel manufacturing process is developed to enable the production of rolled actuators without a hollow core, with a focus on simplicity and reliability. In this way, actuator systems with high energy density can be effectively achieved. After presenting the design, an experimental evaluation of the CORDEA electromechanical behavior is performed. Finally, actuator experiments in which the CORDEA is pre-loaded with a mass load and subsequently subject to cycling voltage are illustrated, and the resulting performance is discussed.

Soft Freestanding Planar Artificial Muscle Based on Dielectric Elastomer Actuator

2018 ◽  
Vol 85 (5) ◽  
Author(s):  
Lei Qin ◽  
Jiawei Cao ◽  
Yucheng Tang ◽  
Jian Zhu
Keyword(s):  
Structural Complexity ◽  
Artificial Muscle ◽  
High Energy ◽  
Dielectric Elastomer ◽  
Tactile Feedback ◽  
High Energy Density ◽  
Artificial Muscles ◽  
Dielectric Elastomer Actuators ◽  
Electromechanical Instability ◽  
Compression Springs

Dielectric elastomer actuators (DEAs) exhibit interesting muscle-like attributes including large voltage-induced deformation and high energy density, thus can function as artificial muscles for soft robots/devices. This paper focuses on soft planar DEAs, which have extensive applications such as artificial muscles for jaw movement, stretchers for cell mechanotransduction, and vibration shakers for tactile feedback, etc. Specifically, we develop a soft planar DEA, in which compression springs are employed to make the entire structure freestanding. This soft freestanding actuator can achieve both linear actuation and turning without increasing the size, weight, or structural complexity, which makes the actuator suitable for driving a soft crawling robot. Furthermore, its simple structure and homogeneous deformation allow for analytic modeling, which can be used to interpret the large voltage-induced deformation and interesting mechanics phenomenon (i.e., wrinkling and electromechanical instability). A preliminary demonstration showcases that this soft planar actuator can be employed as an artificial muscle to drive a soft crawling robot.

A Co-Axial Dielectric Elastomer Actuator

2008 ◽  
Vol 61 ◽  
pp. 81-84 ◽  
Author(s):  
Hristiyan Stoyanov ◽  
Guggi Kofod ◽  
Reimund Gerhard
Keyword(s):  
High Energy ◽  
Dip Coating ◽  
Dielectric Elastomer ◽  
Thin Layers ◽  
High Energy Density ◽  
Dielectric Elastomer Actuator ◽  
Dielectric Elastomer Actuators ◽  
Active Layers ◽  
Potential Applications ◽  
Actuation Strain

Dielectric elastomer actuators based on Maxwell-stress induced deformation, are considered for many potential applications where high actuation strain and high energy density are required. They usually rely on a planar actuator configuration, however, a string-like actuator would be less bulky, and more versatile for several applications. In this paper, a co-axial dielectric elastomer actuator that produces relatively high actuation strain is presented. The actuator is manufactured through alternating dip-coating steps with insulating and conductive thin layers. A soluble thermoplastic block-copolymer, SEBS(poly-(styrene-ethylene-butylene-styrene), is used for the dielectric layers as well as for the host material of the compliant electrodes. Electrical conductivity of the electrodes is achieved by incorporation of conductive carbon-black particles in the elastomer matrix. Actuators with a single and with multiple active layers (up to three) have been successfully demonstrated. This geometry is advantageous in that it is compact and can be bundled easily, and should therefore be practical in applications such as “artificial muscles”.

Conductive, self-healing and recyclable electrodes for dielectric elastomer generator with high energy density

2022 ◽  
Vol 429 ◽  
pp. 132258
Author(s):  
Wenpeng Zang ◽  
Xueying Liu ◽  
Junjie Li ◽  
Yingjie Jiang ◽  
Bing Yu ◽  
...  
Keyword(s):  
Energy Density ◽  
High Energy ◽  
Dielectric Elastomer ◽  
High Energy Density ◽  
Self Healing

scholarly journals Sensitivity Analysis of the Transmission Chain of a Horizontal Machining Tool Axis to Design and Control Parameters

2014 ◽  
Vol 6 ◽  
pp. 169064 ◽  
Author(s):  
Stefano Mauro ◽  
Stefano Pastorelli ◽  
Tharek Mohtar
Keyword(s):  
Sensitivity Analysis ◽  
Lumped Parameter Model ◽  
Control Parameters ◽  
Damping Coefficients ◽  
Transmission Chain ◽  
Lumped Parameter ◽  
Tool Axis ◽  
Optimal Value ◽  
Structural Parts ◽  
And Control

This paper reports how a numerical controlled machine axis was studied through a lumped parameter model. Firstly, a linear model was derived in order to apply a modal analysis, which estimated the first mechanical frequency of the system as well as its damping coefficients. Subsequently, a nonlinear system was developed by adding friction through experimentation. Results were validated through the comparison with a commercial servoaxis equipped with a Siemens controller. The model was then used to evaluate the effect of the stiffness of the structural parts of the axis on its first natural frequency. It was further used to analyse precision, energy consumption, and axis promptness. Finally a cost function was generated in order to find an optimal value for the main proportional gain of the position loop.

Dielectric Elastomer Energy Harvesting and its Application to Human Walking

2011 ◽  
Author(s):  
Heather Lai ◽  
Chin An Tan ◽  
Yong Xu
Keyword(s):  
Energy Harvesting ◽  
Knee Joint ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
High Energy ◽  
Dielectric Elastomer ◽  
Metabolic Energy ◽  
High Energy Density ◽  
Human Walking ◽  
Wide Range

Human walking requires sophisticated coordination of muscles, tendons, and ligaments working together to provide a constantly changing combination of force, stiffness and damping. In particular, the human knee joint acts as a variable damper, dissipating greater amounts of energy when the knee undergoes large rotational displacements during walking, running or hopping. Typically, this damping results from the dissipation, or loss, of metabolic energy. It has been proven to be possible however; to collect this otherwise wasted energy through the use of electromechanical transducers of several different types which convert mechanical energy to electrical energy. When properly controlled, this type of device not only provides desirable structural damping effects, but the energy generated can be stored for use in a wide range of applications. A novel approach to an energy harvesting knee joint damper is presented using a dielectric elastomer (DE) smart material based electromechanical transducer. Dielectric elastomers are extremely elastic materials with high electrical permittivity which operate based on electrostatic effects. By placing compliant electrodes on either side of a dielectric elastomer film, a specialized capacitor is created, which couples mechanical and electrical energy using induced electrostatic stresses. Dielectric elastomer energy harvesting devices not only have a high energy density, but the material properties are similar to that of human tissue, making it highly suitable for wearable applications. A theoretical framework for dielectric elastomer energy harvesting is presented along with a mapping of the active phases of the energy harvesting to the appropriate phases of the walking stride. Experimental results demonstrating the energy harvesting capability of a DE generator undergoing strains similar to those experienced during walking are provided for the purpose of verifying the theoretical results. The work presented here can be applied to devices for use in rehabilitation of patients with muscular dysfunction and transfemoral prosthesis as well as energy generation for able-bodied wearers.

Modeling and Control of a High Pressure Combined Air/Fuel Injection System

2009 ◽  
Author(s):  
Chao Yong ◽  
Eric J. Barth
Keyword(s):  
High Pressure ◽  
Fuel Injection ◽  
Lumped Parameter Model ◽  
Injection System ◽  
Fuel Injection System ◽  
Modeling And Control ◽  
Lumped Parameter ◽  
Mass Flow Rates ◽  
And Control ◽  
Liquid Piston

A high pressure combined air-fuel injection system is designed and tested for an experimental free liquid-piston engine compressor. The application discussed utilizes available high pressure air from the compressor’s reservoir, and high pressure fuel to mix and then inject into a combustion chamber. This paper addresses the modeling, design and control for this particular high-pressure air-fuel injection system, which features an electronically controlled air/fuel ratio control scheme. This system consists of a fuel line and an air line, whose mass flow rates are restricted by metering valves. These two lines are connected to a common downstream tube where air and fuel are mixed. By controlling the upstream pressures and the orifice areas of the metering valves, desired A/F ratios can be achieved. The effectiveness of the proposed system is demonstrated by a lumped-parameter model in simulation and validated by experiments.

Design of a Compliant Industrial Gripper Driven by a Bistable Shape Memory Alloy Actuator

2020 ◽  
Author(s):  
Dominik Scholtes ◽  
Stefan Seelecke ◽  
Gianluca Rizzello ◽  
Paul Motzki
Keyword(s):  
Shape Memory ◽  
High Energy ◽  
Industrial Applications ◽  
High Energy Density ◽  
Small Scale ◽  
Monitoring And Control ◽  
Actuation System ◽  
First Results ◽  
Functional Prototype ◽  
And Control

Abstract Within industrial manufacturing most processing steps are accompanied by transporting and positioning of workpieces. The active interfaces between handling system and workpiece are industrial grippers, which often are driven by pneumatics, especially in small scale areas. On the way to higher energy efficiency and digital factories, companies are looking for new actuation technologies with more sensor integration and better efficiencies. Commonly used actuators like solenoids and electric engines are in many cases too heavy and large for direct integration into the gripping system. Due to their high energy density shape memory alloys (SMA) are suited to overcome those drawbacks of conventional actuators. Additionally, they feature self-sensing abilities that lead to sensor-less monitoring and control of the actuation system. Another drawback of conventional grippers is their design, which is based on moving parts with linear guides and bearings. These parts are prone to wear, especially in abrasive environments. This can be overcome by a compliant gripper design that is based on flexure hinges and thus dispenses with joints, bearings and guides. In the presented work, the development process of a functional prototype for a compliant gripper driven by a bistable SMA actuation unit for industrial applications is outlined. The focus lies on the development of the SMA actuator, while the first design approach for the compliant gripper mechanism with solid state joints is proposed. The result is a working gripper-prototype which is mainly made of 3D-printed parts. First results of validation experiments are discussed.

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