Dielectric elastomer actuators (DEAs) have received a lot of attention in the last decade due to their outstanding actuation strain, high energy density, high degree of freedom, electromechanical coupling and low price. However, modelling of dielectric elastomer actuators is complicated because of time-dependent viscoelasticity, complex geometry, electromechanical coupling and material nonlinearity. For these reasons, just a few research results focusing on modeling of the DEAs have been published. In this research, taking into account the influence of viscoelasticity, we present a physical and phenomenal based model to characterize the behaviour of a conical DEA made of polydimethylsiloxane. The nonequilibrium thermodynamic framework is used to characterize the mechanical coupling of DEA. Also, free energy and viscoelastic characteristics of DEA are described using the Gent model and the generalized Kelvin model, respectively. The differential evolution approach is used to find the model parameters based on the experimental data. The model's validity and generalization are proved by comparing experimental results with model predictions, for both different driving input frequencies and amplitudes. The experimental results demonstrate a high level of agreement with the developed model.
Dielectric Elastomers as Electromechanical Transducers provides a comprehensive and updated insight into dielectric elastomers; one of the most promising classes of polymer-based smart materials and technologies. This technology can be used in a very broad range of applications, from robotics and automation to the biomedical field. The need for improved transducer performance has resulted in considerable efforts towards the development of devices relying on materials with intrinsic transduction properties. These materials, often termed as “smart or “intelligent , include improved piezoelectrics and magnetostrictive or shape-memory materials. Emerging electromechanical transduction technologies, based on so-called ElectroActive Polymers (EAP), have gained considerable attention. EAP offer the potential for performance exceeding other smart materials, while retaining the cost and versatility inherent to polymer materials. Within the EAP family, “dielectric elastomers , are of particular interest as they show good overall performance, simplicity of structure and robustness. Dielectric elastomer transducers are rapidly emerging as high-performance “pseudo-muscular actuators, useful for different kinds of tasks. Further, in addition to actuation, dielectric elastomers have also been shown to offer unique possibilities for improved generator and sensing devices. Dielectric elastomer transduction is enabling an enormous range of new applications that were precluded to any other EAP or smart-material technology until recently. This book provides a comprehensive and updated insight into dielectric elastomer transduction, covering all its fundamental aspects. The book deals with transduction principles, basic materials properties, design of efficient device architectures, material and device modelling, along with applications. Concise and comprehensive treatment for practitioners and academics Guides the reader through the latest developments in electroactive-polymer-based technology Designed for ease of use with sections on fundamentals, materials, devices, models and applications
The 9-volume set LNAI 14267-14275 constitutes the proceedings of the 16th International Conference on Intelligent Robotics and Applications, ICIRA 2023, which took place in Hangzhou, China, during July 5–7, 2023. The 413 papers included in these proceedings were carefully reviewed and selected from 630 submissions. They were organized in topical sections as follows: Part I: Human-Centric Technologies for Seamless Human-Robot Collaboration; Multimodal Collaborative Perception and Fusion; Intelligent Robot Perception in Unknown Environments; Vision-Based Human Robot Interaction and Application. Part II: Vision-Based Human Robot Interaction and Application; Reliable AI on Machine Human Reactions; Wearable Sensors and Robots; Wearable Robots for Assistance, Augmentation and Rehabilitation of Human Movements; Perception and Manipulation of Dexterous Hand for Humanoid Robot. Part III: Perception and Manipulation of Dexterous Hand for Humanoid Robot; Medical Imaging for Biomedical Robotics; Advanced Underwater Robot Technologies; Innovative Design and Performance Evaluation of Robot Mechanisms; Evaluation of Wearable Robots for Assistance and Rehabilitation; 3D Printing Soft Robots. Part IV: 3D Printing Soft Robots; Dielectric Elastomer Actuators for Soft Robotics; Human-like Locomotion and Manipulation; Pattern Recognition and Machine Learning for Smart Robots. Part V: Pattern Recognition and Machine Learning for Smart Robots; Robotic Tactile Sensation, Perception, and Applications; Advanced Sensing and Control Technology for Human-Robot Interaction; Knowledge-Based Robot Decision-Making and Manipulation; Design and Control of Legged Robots. Part VI: Design and Control of Legged Robots; Robots in Tunnelling and Underground Space; Robotic Machining of Complex Components; Clinically Oriented Design in Robotic Surgery and Rehabilitation; Visual and Visual-Tactile Perception for Robotics. Part VII: Visual and Visual-Tactile Perception for Robotics; Perception, Interaction, and Control of Wearable Robots; Marine Robotics and Applications; Multi-Robot Systems for Real World Applications; Physical and Neurological Human-Robot Interaction. Part VIII: Physical and Neurological Human-Robot Interaction; Advanced Motion Control Technologies for Mobile Robots; Intelligent Inspection Robotics; Robotics in Sustainable Manufacturing for Carbon Neutrality; Innovative Design and Performance Evaluation of Robot Mechanisms. Part IX: Innovative Design and Performance Evaluation of Robot Mechanisms; Cutting-Edge Research in Robotics.
Over the past two decades, electroactive polymers (EAP) have been studied as a material for soft actuator and sensor systems. Dielectric elastomers (DE) are an EAP material which relies on the electrostatic force produced on compliant electrodes to produce deformation. In the converse sense, DE sensors can be used by measuring the electrical energy or impedance change produced under deformation. The two key limitations barring DE from commercial use are high driving voltage, and low output force. The scope of this work is as follows: to improve upon these two limitations by processing of actuators by a pneumatic dispenser, by adding tactile sensing and variable stiffness properties to the actuators, and developing a mechanical model to predict the actuator behavior. This work focuses specifically on the unimorph dielectric elastomer actuator (DEA), which consists of a DE laminate which contracts in the thickness direction and expands in-plane under applied voltage, and is constrained on one face by a passive material, resulting in bending of the structure. The first part of the work is devoted to fabrication, modeling, and characterization of multilayer unimorph DEA. Fabrication is done using two schemes – the first is a conventional one, using commercially available DE films, and the second is a novel method using a robotic dispenser system. The latter technique has two objectives. The first is to reduce the thickness of the DE layers to reduce driving voltage, since the DE deformation is proportional to the square of the applied electric field which itself is inversely proportional to electrode separation. The second is to deposit higher-performance DE materials, in this case, PVDF terpolymer, which exhibits large actuation stresses because of its high dielectric constant and relatively high Young’s modulus. Using the dispenser, DE layers with 10 μm thick layers are repeatably produced, requiring actuation voltages one order of magnitude less than conventional thick DE films. Standard deviation of displacement and blocking force do not exceed 10% and 15% of the mean after 2 minutes of deformation, respectively. Elastic and viscoelastic models are developed for multilayer unimorph DEA consisting of flat and curved geometries. Both models were validated in comparison with experimental data with the latter shown to agree with the experimental data to within one standard deviation of the mean for majority of the deformation. The second section demonstrates the novel use of electrolaminates to create variable stiffness DEA (VSDEA). Variable stiffness structures are of particular interest for soft actuators, because they allow switching between a low stiffness, high displacement mode and a high stiffness mode with large holding force. One device is demonstrated by simply utilizing the passive layer of a DEA as part of an electrolaminate, allowing for four-fold increase in bending rigidity. Another device is demonstrated consisting of a bundle of parallel DEA with electrostatic chucking features to modulate shear strength of the interfaces. This device exhibits a 39-fold increase in stiffness, and a claw actuator using these actuators is capable of lifting an object 17 times its own weight. The final part of this work investigates two novel tactile sensors based on dielectric elastomers (DES). The first uses a dome-shaped protrusion to redistribute tactile forces onto an array of four capacitive sensors. The change in capacitance of the four sensors is used to measure and discriminate the force components of the impinging force. An array of these dome DES are fabricated using the dispenser system, and the ability to differentiate between normal and shear forces was demonstrated, as well as its proximity sensing ability. The tactile sensor array is also shown integrated as the passive layer of a DEA, providing tactile and proximity sensing capability to the actuator. The second tactile sensor features high resolution and scalability, and is built in to a medical assistive device coined the “artery mapper” and is used to determine the location of a target artery for arterial line placement. It is demonstrated locating an artery on a test subject, possible due to its force resolution on the order of 2.8 kPa.
This book covers the fundamental properties, modeling, and demonstration of Electroactive polymers in robotic applications. It particularly details artificial muscles and sensors. In addition, the book discusses the properties and uses in robotics applications of ionic polymer–metal composite actuators and dielectric elastomers.
Constitutive Models for Rubber XII is a comprehensive compilation of the oral and poster contributions to the XII European Conference on Constitutive Models for Rubbers (Milan, Italy, 7-9 September 2022). As the first after the COVID Pandemic, the XII edition again brought together researchers from the industry and the academia working in the field of elastomer technology and science to discuss the most recent advancement in the following topics: • Constitutive models • Micro-structural investigations • Experimental methods and characterization • Numerical methods • Fatigue and fracture • Aging • Industrial applications • Smart elastomer materials: applications and modelling Including more than 80 contributions from authors from around the world, this book aims at professionals and academics interested in elastomer technology and science.
Dielectric elastomer actuator (DEA) is a key element for the soft robots, which has received increasing attention. However, the main difficulties in modeling soft actuators such as dielectric elastomer actuators are time-dependent viscoelasticity and their material nonlinearity. It is important to consider the viscoelasticity of the dielectric elastomer (DE) to fully understand its mechanical behavior. However, so far only a few works have been presented considering the viscoelasticity of the DE material together with the effect of temperature and deformation. In this thesis, a dynamic electromechanical-coupled model for a rectangle dielectric elastomer a commonly used material (the acrylic elastomer VHB 4910) has been proposed, with taking into consideration of the influence of temperature, voltage, and frequency on the DE. The proposed model is based on the free energy physical-based principle, where the general Kelvin-Voigt model is applied to describe the viscoelasticity of the DE, and the Maxwell force together with the Electrostrictive force are considered. The influence of temperature and deformation on the DE is included in this model. The model in this study is a dynamic electromechanical model of a DE actuator, and can effectively describe the dynamic characteristics of the DE. By using the Differential Evolution, the model parameters were identified. The model was implemented and simulated in MATLAB, and the simulation and the actual experiment agrees to a great extent. The experimental test conducted in this study matches with the simulations results, which means that the proposed model can be practical to predict and describe DEAs electromechanical and viscoelastic behavior. Predicting the electromechanical and viscoelastic behavior of the DE is extremely useful for controlling a viscoelastic DEA and paving the way to improve the control performance, and also develops applications in soft robotics.
Dielectric elastomer (DE) is an important kind of electro active polymer. Its softness and unique movement generating mechanism make people recognize it as artificial muscle. Existing studies focusing on it have revealed many important properties of this soft material. Fundamental researches show the working principle of how DE material can convert electrical energy and mechanical energy bi-directionally. Various actuators, devices, and robots are also developed to show the great potential of DE material in future applications. However, DE material’s nonlinear visco-elasticity and uncommon configuration in applications pose significant challenge in the developing of practical DE applications. Starting from the very basics of DE material, the working principle, modeling work, and famous applications are reviewed. Based on these fundamental knowledge of DE material, fabrications of two types of DE actuators are attempted, which demonstrate and verify the promising usage of DE material in future’s soft actuator and robotic applications. DE material’s movement generating mechanism also gives the capability of self-sensing. Software methods, including polynomial fitting and artificial neural network, are used to realize the self-sensing function in DE actuator. Different applications of DE actuators are attempted. A DE diaphragm actuator for human pulse tracking purpose is designed, fabricated, and tested. Experimental results show it can convert human pulse data into compliant vibration with good accuracy, which shows it has great potential in future’s medical applications. By patterning the diaphragm actuator’s electrode, a new type of 2-DoF maneuverable lase manipulator is created. The manipulator is capable of tracking 2-DoF angular reference with soft and gearless structure. It is expected that this new type laser manipulator can be used in laser servo system under special environment.
