A nonlinear, control-oriented model for ionic polymer-metal composite actuators
A nonlinear, control-oriented model for ionic polymer-metal composite actuators
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DOI：
10.1088/0964-1726/18/5/055008
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发表时间：
2009-05-01
影响因子：
4.1
通讯作者：
Tan, Xiaobo
中科院分区：
文献类型：
--
作者：
Chen, Zheng;Hedgepeth, Dawn Rochelle;Tan, Xiaobo
离子聚合物-金属复合材料（IPMCs）是一类重要的电活性聚合物，在生物医学、机器人和微/纳米操作系统中具有广泛的应用前景。本文提出了一种非线性的、面向控制的IPMC执行器模型。该模型的一个关键组成部分是IPMC的非线性电容。在非线性电容的推导中，充分考虑了非线性偏微分方程（PDE），该方程可以捕捉到IPMC的基本物理特性。从系统的角度，通过解析求解阶跃电压作用下稳态的非线性偏微分方程，得到了电压到感应电荷的非线性映射。非线性电容被纳入电路模型，其中还包括由电化学吸附过程引起的伪电容、离子扩散电阻和聚合物的非线性直流电阻，以捕获IPMC的电动力学。在机电耦合的情况下，根据电路模型推导出曲率输出。所提出的模型是在状态空间中表述的，这将是非线性控制器设计的起点。实验验证表明，所提出的模型能够捕捉到IPMC电响应中的主要非线性。
Ionic polymer-metal composites (IPMCs) form an important category of electroactive polymers and have many potential applications in biomedical, robotic and micro/nanomanipulation systems. In this paper, a nonlinear, control-oriented model is proposed for IPMC actuators. A key component in the proposed model is the nonlinear capacitance of the IPMC. A nonlinear partial differential equation (PDE), which can capture the fundamental physics in the IPMC, is fully considered in the derivation of nonlinear capacitance. A systems perspective is taken to get the nonlinear mapping from the voltage to the induced charge by analytically solving the nonlinear PDE at the steady state when a step voltage is applied. The nonlinear capacitance is incorporated into a circuit model, which includes additionally the pseudocapacitance due to the electrochemical adsorption process, the ion diffusion resistance, and the nonlinear DC resistance of the polymer, to capture electrical dynamics of the IPMC. With electromechanical coupling, the curvature output is derived based on the circuit model. The proposed model is formulated in the state space, which will be the starting point for nonlinear controller design. Experimental verification shows that the proposed model can capture the major nonlinearities in the electrical response of the IPMC.