Biomedical engineering applications of ionic polymer-metal composites such as motion devices for endoscopy, pumps, valves, catheter navigation mechanisms and spinal pressure sensors make it important to properly model IPMCs for engineering design. In particular, IPMC continuum models and their electric equivalent circuit representation are critical to a more efficient design of IPMC devices. In this paper, we propose a new continuum electromechanical model to understand and predict the electrical/mechanical behavior of the IPMC. An IPMC lumped-parameter circuit is derived from its continuum model to predict the relationship between its voltage and current signals. Although based on previous works of Shahinpoor and Nemat-Nasser, our model was derived on a macroscopic level, the water effects were assumed negligible when compared with the electrical effects of mobile ions for the IPMC motion, the model parameters were clearly identified in their physical meaning, and an equivalent-circuit IPMC model was determined from the established continuum electromechanical model. Experiments are done with two IPMC pieces having different dimensions, which were previously immersed in a sodium solution. The IPMCs are current driven, the transverse displacement and voltage signals being measured for different current values, avoiding the water electrolysis phenomenon. Simulations using the analytic models derived are compared with the experimental results and they are found to predict the electrical and mechanical relations very accurately.
This paper presents an analytical, numerical and experimental study of an asymmetric piezoelectric actuator/sensor cantilever beam. The structure consists in a three-layered laminate with a piezoceramic acting as actuator, an elastic material layer and a second piezoceramic layer that can operate as a sensor or actuator. The coupled expansion-bending motion of the system is analytically resolved, where the governing electromechanical expansion and bending motion equations are obtained. Explicitly analytic solutions for longitudinal and transverse displacements, and also the mechanical/electrical frequency response of the structure are calculated. A finite element model (FEM) is developed and used to evaluate the accuracy of the analytic model. Experimental results are used to verify the frequency response of the structure, and validate the theoretical and FEM models.
Formal language techniques have been used in the past to study autonomous dynamical systems. However, for controlled systems, new features are needed to distinguish between information generated by the system and input control. We show how the modelling framework for controlled dynamical systems leads naturally to a formulation in terms of context-dependent grammars. A learning algorithm is proposed for on-line generation of the grammar productions, this formulation being then used for modelling, control and anomaly detection. Practical applications are described for electromechanical drives. Grammatical interpolation techniques yield accurate results and the pattern detection capabilities of the language-based formulation makes it a promising technique for the early detection of anomalies or faulty behaviour.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.