This paper describes a linear dynamic model of an elongated bending Electroactive Polymer (EAP) actuator applicable
with deformations of any magnitude. The model formulates relation of a) voltage applied to the EAP sheet, b) current
passing through the EAP sheet, c) force applied by the actuator and d) deformation of the actuator. In this model only the
geometry of EAP piece and four empirical parameters of the EAP material: a) bending stiffness, b) electromechanical
coupling term, c) electrical impedance and d) initial curvature are considered. The contribution of this paper is
introducing a model that can be used to characterize the properties of different EAP materials and compare them. The
advantage of the model is its simplicity and ability to provide insights in to the behavior of bending EAPs. Additionally,
due to linearity of the model, the real-time control is feasible. Experiments, using Ionomeric Polymer-Metal Composite
(IPMC) sheet from Environmental Robotics Inc., where carried out to verify the model. The experimental results confirm
the model is valid.
This paper presents a distributed model of an IPMC (Ionomeric Polymer-Metal Composite). Unlike other
electromechanical models of an IPMC, the distributed nature of our model permits modelling the non-uniform bending
of the material. Instead of modeling solely the tip deflection of the material, we model the changing curvature. Our
model of the IPMC describes the actuator or sensor as a distributed one-dimensional RC transmission line. The behavior
of the IPMC at its each particular position in time-domain is described by a system of Partial Differential Equations.
(PDE). The parameters of the PDE-s have a clear physical interpretation: the conductivity of the electrodes, the
pseudocapacitance of the arising double-layer at the boundary of the electrodes, the electric current caused by electrode
reactions etc. The electromechanical coupling between the electrical parameters and the bending motion is implemented
by means of distribution of electric current along the material in a time domain. The distributed nature of the model
permits predicting the non-uniform bending of the IPMC actuators in time domain or to reconcile the output of an IPMC-based
position sensor with its shape. Taking into account several nonlinear parameters, the model is consistent with the
experimental results even when the inflexion of the actuator or sensor is large or the water electrolysis appears.
IPMC (Ionic Polymer Metal Composite) is a class of electroactive polymers (EAP) that bend when electric field is
applied to the material. From our theoretical studies of the material it appears that IPMC can be modelled as a lossy
transmission line. From simulations it appears that IPMC reaction time depends on length of the strip used. Also the
shorter the transmission line the less complex it is to model. We have also mechanically modeled an IPMC. It appears
that the output force does not depend on length on IPMC but on width. Also the shape unpredictability is the larger the
longer the strip is. Based on these results the concept of a short IPMC with rigid extension was created. From
simulations and experiments it was seen that there exists a certain length of IPMC at which output force and deflection
angle remain close to those of a long IPMC while precision increases. Also, the material becomes easier to model and its
short-term stability appears to be sufficient to be controlled. A manipulator was built to verify IPMC compatibility as
links, tested for accuracy and compared with a long sheet of IPMC. The manipulator appeared to be 314% more accurate
and twice as fast compared to the long strip of an IPMC and thus confirming the usability of the described design.
We study ionomeric polymer-metal composite (IPMC) actuators in situations where the strip of actuator acts either on maximum mechanical power or maximum amplitude of actuation. We apply a modified equivalent circuit of IPMC muscle which takes into account the surface resistance change while material bends. In case of series of bending acts, the first actuation of IPMC actuator is performed by a relaxed actuator, it bends over it's full length. During the next movements the most of the energy is caught by fore-part of actuator. The explanation of that effect is given.