Design of a Command-Shaping Scheme for Mitigating Residual Vibrations in Dielectric Elastomer Actuators

2019 ◽  
Vol 87 (2) ◽  
Author(s):  
Atul Kumar Sharma
Keyword(s):  
Equilibrium State ◽  
Input Signal ◽  
Virtual Work ◽  
Dielectric Elastomer ◽  
Force Balance ◽  
Command Shaping ◽  
Dielectric Elastomer Actuators ◽  
Electromechanical Transduction ◽  
Control Scheme ◽  
Wide Range

Abstract Dielectric elastomers (DEs) are a class of highly deformable electroactive polymers (EAPs) employed for electromechanical transduction technology. When electrostatically actuated dielectric elastomer actuators (DEAs) are subjected to an input signal comprising multiple Heaviside voltage steps, the emerging inherent residual vibrations may limit their motion accuracy in practical applications. In this paper, the systematic development of a command-shaping scheme is proposed for controlling residual vibrations in an electrically driven planar DEA. The proposed scheme relies on invoking the force balance at the point of maximum lateral stretch in an oscillation cycle to bring the actuator to a stagnation state followed by the application of an additional electric input signal of predetermined magnitude at a specific time. The underlying concept of the proposed control scheme is articulated for a single Heaviside step input-driven actuator and further extended to the actuator subjected to the multistep input signal. The equation governing the dynamic motion of the actuator is derived using the principle of virtual work. The devised dynamic model of the actuator incorporates the effects of strain stiffening of elastomer and viscous energy dissipation. The nonlinear dynamic governing equation is solved using matlab ode solver for extracting the dynamic response of the actuator. The applicability of the devised command-shaping control scheme is illustrated by taking a wide range of parameters including variations in the extent of equilibrium state sequences, damping, and polymer chain extensibility. The proposed scheme is found to be adaptable in controlling the vibrations of the actuator for any desired equilibrium state. The results presented in this paper can find its potential application in the design of an open-loop control system for DEAs.

Properties of a Dielectric Elastomer Actuator Modified by Dispersion of Functionalised Carbon Nanotubes

2012 ◽  
Vol 79 ◽  
pp. 41-46 ◽  
Author(s):  
Fabia Galantini ◽  
Sabrina Bianchi ◽  
Valter Castelvetro ◽  
Irene Anguillesi ◽  
Giuseppe Gallone
Keyword(s):  
Carbon Nanotubes ◽  
Dielectric Constant ◽  
Mechanical Performance ◽  
Broad Class ◽  
Dielectric Elastomer ◽  
Low Dielectric ◽  
Dielectric Elastomer Actuators ◽  
Electromechanical Transduction ◽  
The Matrix ◽  
Simple Matrix

Among the broad class of electro-active polymers, dielectric elastomer actuators represent a rapidly growing technology for electromechanical transduction. In order to further develop this applied science, the high driving voltages currently needed must be reduced. For this purpose, one of the most promising and adopted approach is to increase the dielectric constant while maintaining both low dielectric losses and high mechanical compliance. In this work, a dielectric elastomer was prepared by dispersing functionalised carbon nanotubes into a polyurethane matrix and the effects of filler dispersion into the matrix were studied in terms of dielectric, mechanical and electro-mechanical performance. An interesting increment of the dielectric constant was observed throughout the collected spectrum while the loss factor remained almost unchanged with respect to the simple matrix, indicating that conductive percolation paths did not arise in such a system. Consequences of the chemical functionalisation of carbon nanotubes with respect to the use of unmodified filler were also studied and discussed along with rising benefits and drawbacks for the whole composite material.

scholarly journals Dielectric Elastomer Actuator Driven Soft Robotic Structures With Bioinspired Skeletal and Muscular Reinforcement

2020 ◽  
Vol 7 ◽  
Author(s):  
M. Franke ◽  
A. Ehrenhofer ◽  
S. Lahiri ◽  
E.-F. M. Henke ◽  
T. Wallmersperger ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Aerosol Deposition ◽  
Dielectric Elastomer ◽  
Artificial Muscles ◽  
Soft Systems ◽  
Natural Motion ◽  
Dielectric Elastomer Actuators ◽  
Resonance Frequencies ◽  
Wide Range ◽  
Laminate Theory

Natural motion types found in skeletal and muscular systems of vertebrate animals inspire researchers to transfer this ability into engineered motion, which is highly desired in robotic systems. Dielectric elastomer actuators (DEAs) have shown promising capabilities as artificial muscles for driving such structures, as they are soft, lightweight, and can generate large strokes. For maximum performance, dielectric elastomer membranes need to be sufficiently pre-stretched. This fact is challenging, because it is difficult to integrate pre-stretched membranes into entirely soft systems, since the stored strain energy can significantly deform soft elements. Here, we present a soft robotic structure, possessing a bioinspired skeleton integrated into a soft body element, driven by an antagonistic pair of DEA artificial muscles, that enable the robot bending. In its equilibrium state, the setup maintains optimum isotropic pre-stretch. The robot itself has a length of 60 mm and is based on a flexible silicone body, possessing embedded transverse 3D printed struts. These rigid bone-like elements lead to an anisotropic bending stiffness, which only allows bending in one plane while maintaining the DEA's necessary pre-stretch in the other planes. The bones, therefore, define the degrees of freedom and stabilize the system. The DEAs are manufactured by aerosol deposition of a carbon-silicone-composite ink onto a stretchable membrane that is heat cured. Afterwards, the actuators are bonded to the top and bottom of the silicone body. The robotic structure shows large and defined bimorph bending curvature and operates in static as well as dynamic motion. Our experiments describe the influence of membrane pre-stretch and varied stiffness of the silicone body on the static and dynamic bending displacement, resonance frequencies and blocking forces. We also present an analytical model based on the Classical Laminate Theory for the identification of the main influencing parameters. Due to the simple design and processing, our new concept of a bioinspired DEA based robotic structure, with skeletal and muscular reinforcement, offers a wide range of robotic application.

Energy Optimal Control of Dielectric Elastomer Actuators via Adaptive Dynamic Programming

2019 ◽  
Author(s):  
Paolo Roberto Massenio ◽  
David Naso ◽  
Gianluca Rizzello
Keyword(s):  
Optimal Control ◽  
Dynamic Programming ◽  
Dielectric Elastomer ◽  
Adaptive Dynamic Programming ◽  
Set Point ◽  
Adaptive Dynamic ◽  
Strongly Nonlinear ◽  
Dielectric Elastomer Actuators ◽  
Control Scheme ◽  
Dielectric Elastomer Membrane

Abstract This paper presents an optimal motion control scheme for a mechatronic actuator based on a dielectric elastomer membrane transducer. The optimal control problem is formulated such that a desired position set-point is reached with minimum amount of driving energy, characterized via an accurate physical model of the device. Since the considered actuator is strongly nonlinear, an approximated approach is required to practically address the design of the control system. In this work, an Adaptive Dynamic Programming based algorithm is proposed, capable of minimizing a cost function related to the energy consumption of the considered system. Simulation results are presented in order to assess the effectiveness of the proposed method, for different set-point regulation scenarios.

Improved Materials for Dielectric Elastomer Actuators

2008 ◽  
Author(s):  
Dorina Opris ◽  
Martin Molberg ◽  
Christiane Lo¨we ◽  
Frank Nu¨esch ◽  
Christopher Plummer ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Dielectric Constant ◽  
Electroactive Polymers ◽  
Dielectric Elastomer ◽  
Electromechanical Properties ◽  
Silicone Elastomers ◽  
Broad Application ◽  
Dielectric Elastomer Actuators ◽  
Electromechanical Transduction ◽  
Doped Polyaniline

Dielectric elastomers are an emerging class of electroactive polymers for electromechanical transduction. A broad application of dielectric elastomer actuators (DEA) is limited by the high voltage necessary to drive such devices. The development of novel elastomers offering better intrinsic electromechanical properties is one way to solve the problem. Therefore we prepared composites from thermoplastic or thermoset silicone elastomers and organic fillers as phthalocyanines or doped polyaniline (PANI). We studied the mechanical properties of silicones, synthesized, modified and characterized phthalocyanines and doped PANI. The influence of humidity onto the dielectric properties of CuPc(COOH)8 and ZnPc(COOH)8 was analyzed in detail. First measurements of silicone/PANI blends results in a hundredfold increase for the dielectric constant and an electromechanically strain of 8.5%.

scholarly journals A broadbanded pressure differential wave energy converter based on dielectric elastomer generators

2021 ◽  
Author(s):  
Michele Righi ◽  
Giacomo Moretti ◽  
David Forehand ◽  
Lorenzo Agostini ◽  
Rocco Vertechy ◽  
...  
Keyword(s):  
Wave Energy ◽  
Large Deformations ◽  
Dielectric Elastomer ◽  
Wave Energy Converter ◽  
Pressure Differential ◽  
Design Stage ◽  
Small Scale ◽  
Energy Converter ◽  
Wide Range ◽  
The Waves

AbstractDielectric elastomer generators (DEGs) are a promising option for the implementation of affordable and reliable sea wave energy converters (WECs), as they show considerable promise in replacing expensive and inefficient power take-off systems with cheap direct-drive generators. This paper introduces a concept of a pressure differential wave energy converter, equipped with a DEG power take-off operating in direct contact with sea water. The device consists of a closed submerged air chamber, with a fluid-directing duct and a deformable DEG power take-off mounted on its top surface. The DEG is cyclically deformed by wave-induced pressure, thus acting both as the power take-off and as a deformable interface with the waves. This layout allows the partial balancing of the stiffness due to the DEG’s elasticity with the negative hydrostatic stiffness contribution associated with the displacement of the water column on top of the DEG. This feature makes it possible to design devices in which the DEG exhibits large deformations over a wide range of excitation frequencies, potentially achieving large power capture in a wide range of sea states. We propose a modelling approach for the system that relies on potential-flow theory and electroelasticity theory. This model makes it possible to predict the system dynamic response in different operational conditions and it is computationally efficient to perform iterative and repeated simulations, which are required at the design stage of a new WEC. We performed tests on a small-scale prototype in a wave tank with the aim of investigating the fluid–structure interaction between the DEG membrane and the waves in dynamical conditions and validating the numerical model. The experimental results proved that the device exhibits large deformations of the DEG power take-off over a broad range of monochromatic and panchromatic sea states. The proposed model demonstrates good agreement with the experimental data, hence proving its suitability and effectiveness as a design and prediction tool.

Sign in / Sign up

Export Citation Format

Share Document