When dielectric elastomer actuators (DEAs) are used in micro-scale applications, the resulting area-to-thickness ratio is expected to be much smaller in comparison to that of macro-scale systems. In this case, local effects such as fringing field are expected to have a non-negligible impact on the resulting actuator behavior. As a result, numerical predictions obtained via conventional models, which in turn are based on uniform field assumptions, are expected no longer to be accurate. Motivated by the need to develop and optimize micro-scale DEA applications, this paper presents a numerical study on how the electro-mechanical performances of a DEA are affected when reducing the system scale. In-plane and out-of-plane DEA configurations are investigated via dedicated finite element simulations, in which the system relative dimensions are progressively decreased, and the performance are evaluated in terms of both mechanical (i.e., stroke/force) and electrical (i.e., capacitance) response. The finite element predictions are then compared with the results obtained via commonly used lumped-parameter models based on uniform field distributions. The results obtained provide insights into the scale at which the performance of DEAs can no longer be explained with conventionally used lumped-parameter models, and will pave the way for future DEA cooperative micro-actuator applications.
Dielectric elastomer (DE) transducers are promising candidates for the development soft cooperative actuator systems, due to their high compliance, stretchability, lightweight, and intrinsic self-sensing capabilities. By combining several DE micro-actuators and arranging them as an array, cooperative devices such as distributed loudspeakers, soft robots, and wearable devices can be created. To achieve an effective interaction among the individual actuators and accomplish a shared task, feedback control strategies are required. In the case of cooperative DE devices, a way to fulfil the demanding requirements of lightness, compactness, and flexibility is to exploit the intrinsic material self-sensing capability. Cooperative self-sensing paradigms allow several interconnected actuators to estimate their own displacement as well as the one of their neighbors based on electrical measurement only, and use this information as a feedback for implementing a cooperative control task. In this paper, we investigate for the first time a self-sensing approach for cooperative DE actuator systems. A soft array of 1-by-3 DE elements is used as case of study. Since a single soft membrane is shared across the different actuating DEs, the capacitance of each element in the array changes by a different amount depending on which DE is actuated and/or deformed. Building upon established self-sensing algorithms for single-degree-of-freedom DE actuators, we experimentally investigate the relationship between the DEs capacitive state and the array deformation state, with the goal of reconstructing the latter based on the former for different actuation patterns (corresponding to different combinations of DEs being actuated). These results will pave the way for the future development of cooperative control algorithms for interconnected DE array systems.
In this work, we present on the characterization of the mechanical coupling in an array system of independent dielectric elastomer (DE) elements. The target device consists of a 1-by-3 array of silicone-based DE elements on a single silicone membrane. This DE-array is the basis for the development of a future DE-actuator array. To achieve large strokes in this DEA-array, the goal is to bias every DE element with a suitable nonlinear biasing element. A correct design of all biasing elements requires the knowledge of how the biasing of one DE-element influences the others and vice versa. After describing the potential influences of the coupling on the correct actuator design, a possible characterization method for the investigation of the coupling is presented. Furthermore, first results are shown and discussed briefly.
In this paper, we report a modeling and simulation study based on a 1-by-3 soft array of independently controllable dielectric elastomer actuators (DEAs). Based on collected experimental results, a physics-based model is initially developed, calibrated, and validated. Then, the effects of the system parameters (geometry, DEA spatial distribution, pre-loading of non-actuated elements) on the resulting array stroke, as well as on the coupling among neighbor elements, will be investigated via extensive simulations. The obtained results will serve as guidelines for the optimal design of cooperative DEA microarray systems.
By combining small dielectric elastomer (DE) elements in an array configuration, their simultaneous actuation and sensing capabilities can be exploited to develop flexible and energy efficient cooperative systems. In this paper we present development, modelling, and experimental validation of a flexible DE array system. After discussing the system operating principle, a physics-based lumped parameter model is developed to describe the electro-mechanical interactions among the several DE elements. An experimental investigation is also conducted on a first 1-by-3 DE array prototype, with the aim of studying the influence of the geometric parameters on the spatially coupled system response. The experimental data is then used to validate the developed model.
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