Modeling of the effects of the electrical dynamics on the electromechanical response of a DEAP circular actuator with a mass–spring load

Abstract

This paper presents a modeling approach of an actuator system based on a dielectric electro-active polymer (DEAP) circular membrane mechanically loaded with a mass and a linear spring. The motion is generated by the deformation of the membrane caused by the electrostatic compressive force between two compliant electrodes applied on the surface of the polymer. A mass and a linear spring are used to pre-load the membrane, allowing stroke in the out-of-plane direction. The development of mathematical models which accurately describe the nonlinear coupling between electrical and mechanical dynamics is a fundamental step in order to design model-based, high-precision position control algorithms operating in high-frequency regimes (up to 150 Hz). The knowledge of the nonlinear electrical dynamics of the actuator driving circuit can be exploited during the control system design in order to achieve desirable features, such as higher modeling accuracy for high-frequency actuation, self-sensing or control energy minimization. This work proposes a physical model of the DEAP actuator system which couples both electrical and mechanical dynamics occurring during the actuation process. By means of numerous experiments, it is shown that the model can be used to predict both actuator current and displacement, and therefore to increase the overall displacement prediction accuracy with respect to actuator models which neglect electrical behavior.

Performance Optimization of a Conical Dielectric Elastomer Actuator

“…Approximated mathematical models have been developed to characterize the performance of conical DEAs with biasing springs and biasing mass [22][23][24]. Two important simplifying assumptions are made in their models, which include a truncated cone-shape approximation and homogeneous stress distribution on the deformed DEA membrane.…”

“…However, due to the lack of sufficient experimental samples, no optimization and in-depth analysis have been conducted. As has been pointed out by [24,25], the simplifying assumption of a truncated cone shape becomes less valid when the ratio of the inner disk radius to outer ring radius, a/b, becomes smaller, which leads to a greater error in model prediction. A quasi-static analytical model for conical DEA which is based on thermodynamic equilibrium and geometry relationships was developed in [26].…”

Mechanical Simplification of Variable-Stiffness Actuators Using Dielectric Elastomer Transducers

“…This section first reviews a DET electrical model and a cone-diaphragm mechanical model from other works [26][27][28]. It uses the electrical model to give insight into the causes of electrical energy storage and losses in DETs that will be used to interpret the results in Section 4.…”

“…An electrical circuit consisting of a capacitance C with a series resistance R s and parallel resistance R p [26,27] (Figure 4) is a model for the electrical energy stored and dissipated in a DET. Because a DET consists of a pair of electrodes separated by a dielectric, it capacitively stores electrical energy U c according to…”

Reset Strategy for Output Feedback Multiple Models MRAC Applied to DEAP

“…Relying on linear and nonlinear models a wide range of control systems for DEAP actuator was created. In works [7], [8], the PID controller was studied. The feedback control was designed to obtain high precision in work [10] and the compensation of hysteresis was proposed in work [11].…”