Tactile sensation is one of the most important sensory functions along with the auditory sensation for the visually impaired because it replaces the visual sensation of the persons with sight. In this paper, we present a tactile display device as a dynamic
Braille display that is the unique tool for exchanging information
among them. The proposed tactile cell of the Braille display is based on the dielectric elastomer and it has advantageous features over the existing ones with respect to intrinsic softness, ease of fabrication, cost effectiveness and miniaturization. We introduce
a new idea for actuation and describe the actuating mechanism of the Braille pin in details capable of realizing the enhanced spatial density of the tactile cells. Finally, results of psychophysical experiments are given and its effectiveness is confirmed.
It is usual to use sensors for controlling an electrostrictive polymer (EP) actuator system. However, it may make the whole actuator system larger and more complex. Thus, it is quite difficult to use some sensors for building a simple and small EP actuator system. In this paper, a technique based on neural networks is proposed to control a simple EP actuator without any sensor. First, a closed loop controller with a sensor is applied to control this EP actuator and its data are measured. Then these data and the characteristics of EP polymers are used to train a neural network offline. The resultant neural network is applied to control a simple EP actuator with no sensor. The experimental data under the proposed technique are compared with those under the closed loop controller and its result is discussed.
In this paper we present a packaged actuator to be applied for
micro and macro robotic applications. The actuator is based on polymer dielectrics, and intrinsically has musclelike characteristics capable of performing motions such as forward/backward/controllable compliance. The actuator is featured in several aspects such as simplicity and lightness in weight, cost-effectiveness, multiple DOF-actuation, and digital interface. In this paper, its basic concepts are briefly introduced and the issues about design, fabrication and applications are discussed.
A new biomemetic actuator is proposed. The actuator realizes bidirectional actuation since it is with a stretched film antagonistically configured with compliant electrodes. Also, it is distinguished from existing actuators with respect to the controllability of its compliance. Bidirectional actuation and compliance controllability are important characteristics for the artificial muscle actuator and the proposed one accomplishes these requirements without any mechanical substitute or complicated algorithms. In this paper its basic concepts and working principles are introduced with static and dynamic analysis. Control strategies for displacement as well as stiffness are introduced, and experimental results are given to confirm the effectiveness of the proposed methods. In addition, an example of robotic actuating devices is given to confirm the usefulness of the proposed actuator.
Nanocomposites are a new class of composites which are typically nanoparticle-filled polymers. One promising kind of nanocomposite is clay-based and polymer-layered silicates nanocomposites because the starting clay materials are naturally abundant and, also, their intercalation chemistry is well understood at the present time. A certain clay, Montmorillonite (MxAl4- xMgx)Si8O20$(OH4 has two-dimensional layers of their crystal structure lattice where the layer thickness is around 1 nm with the lateral dimension of approximately 30 nm to a few microns. These layers organize themselves to form stacks, so-called the Gallery through a van der Walls gap in between them. In this work, Montmorillonite (MMT) was modified by a cationic surfactant so as to lower its surface energy significantly. Such a process gave rise to favorable intercalation of nanoparticles within the galleries. The obtained XRD patterns and TEM images indicate that the silicate layers are completely and uniformly dispersed (nearly exfoliated) in a continuous polymer matrix of Nafion that has been successfully used as a starting material of ionic polymer-metal composites (IPMC's).
In previous works, the possibility of the electrostrictive polymer as the actuator use has been proved. In this paper we address an actual design of an actuator and an inchworm type robotic mechanism using the electrostrictive polymer. The robot will be developed to move horizontally, vertically with steering capability, aiming for navigation in small tubular structures such as flexible pipes but now in this stage a simple bellows type robot capable of accomplishing the linear movement like that of an inchworm is introduced. The issues about the mechanism design of the prototype, which has already been developed and under the consideration of reduction in size, are discussed and preliminary results of experiments are given.
In this paper first we address experimental works to investigate basic characteristics of IPMC actuators which have not been discussed sufficiently yet. Surface conductivity, displacement and force features are discussed. Also a new actuator is proposed called Artificial Musclelike Linear Actuator (AMuLA) inspired from the actuation principles of the human. The actuator is a linear actuator simulating the mechanical behavior of myofilaments that are the basic units of the human muscle. Multiple IPMC's and electrodes are utilized to mimic the motion of muscles and as a result, musclelike linear motions can be realized. The prototype of AMuLA is introduced and its performance is evaluated.
The actuation of electrostrictive polymer (EP) actuator under electric field is known due to the electrostatic force between the parallel compliant electrodes on both sides of polymer film, which means the magnitude of electric potential between the electrodes is one of the determinative parameters of the actuation. The actuation is also dependent on the material properties such as dielectric constant and elastic modulus of polymers. In order to maximize the actuation behavior, high dielectric constant and low elastic modulus is essential. Dielectric constant of polymers is typically known to lie between 2.5 and 10, and it depends highly upon the frequency of electric field. The elastic modulus of polymeric elastomers is also dependent highly on the mechanical frequency of motion, when the EP actuator is periodically actuated. The mechanical frequency is generally equivalent to the electric one, since the mechanical motion is induced by the changes of the electric field. In this study, the electrostriction behavior was modeled with the response to the applied electric field in view of the dielectric and the mechanical characteristics of polymeric elastomer.
Recently, Electrostrictive polymers (EPs) are studied for micro-actuator, because of similarity of body tissue. Electrostrictive polymers (EPs) are based on the deformation of dielectric elastomer polymer in the presence of an electric field. Modeling of electrostrictive polymer has been studied, which is about voltage and displacement. And there are many parameters such as Young's modulus, voltage, thickness of EPs, pre-strain, dielectric, frequency and temperature which effect to movement of EPs. To do exact modeling, all parameters are included. In order to use as actuator, we accurately understood about the parameter that we refer above. And we have to execute modeling which parameters are considered. We used FEM in order to understand effects of parameters. Specially, because of pre-strain effects are very important, we derive the relations of stress and strain by using elastic strain energy.
Electrostrictive polymers such as silicone, acrylic, and polyurethane can achieve large strain and stress with high electric field. This property can make electrostrictive polymers useful actuators. While there are some limitations in reducing existing actuators, there are few in electrostrictive polymer actuators. Therefore, an electrostrictive polymer can be used to design an actuator of a micro robot system. In this paper, an actuator system, which consists of an electrostrictive polymer actuator and its controller, is designed and is implemented. Major characteristics about this actuator system are measured and are discussed. Also the performance of this actuator system under a control technique is measured.
Behaviors of nafion-based actuators are significantly affected by interfacial area between electrode and polymer electrolyte. Replication method was utilized to manufacture a large surface-area composite actuator. Etched aluminum foil was used as a template for replication using liquid nafion solution. Measurement of double layer charging and scanning electron microscopy indicated that interfacial area was greatly increased by replication method. Higher surface area induced a better bending performance of ionic polymer metal composite (IPMC). In parallel, the effect of cations on IPMC was interpreted with constant current experiment, linear sweep voltammetry and electrochemical impedance spectroscopy. For univalent cations, ion size is the most influencing parameter on ionic mobility inside membrane. However, ion-ion interaction affects an ionic mobility for divalent cations.
The low actuating voltage and quick bending responses of ion-exchange polymer metal composite (IPMC) are considered very attractive for the construction of various types of actuators. The principle of IPMC actuation under electric field has been believed to be the ion cluster flux and electro-osmotic drag of water from anode to cathode direction through the hypothetical hydrophilic channels in the perfluorinated sulfonic acid polymer chains. In this study, the effect of water content residing in the perfluorinated polymer was investigated in terms of CV (cyclic voltammetry response, deformation, and bending moment. As a preliminary result of DSC thermal analysis, the water residing in the IPMC actuator seems to reside as free water and bound water, each corresponding to interstitial and hydrogen-bonded water molecules. Using the classical lamination theory (CLT), a modeling methodology was developed to predict the deformation, bending moment, and residual stress distribution of anisotropic IPMC thin plates. In this modeling methodology, the internal stress evolved by the unsymmetric distribution of water inside IPMC was quantitatively calculated and subsequently the bending moment and the curvature were estimated for various geometry of IPMC actuator. The model prediction and experimental results were compared well with practical observation and experimental results demonstrating the validity of the developed modeling methodology.
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