Abstract: The composite structure with the dielectric elastomer and soft materials is the main form of the actuators in soft robots. However, the theoretical model is hard to obtain due to the nonlinear large deformation of materials. In this paper, a new composite element model is established based on the absolute nodal coordinate formulation. The consistent deformation conditions at the contact interface between two thin plates are deduced. The hyperelastic constitutive model and the dielectric elastomer constitutive model are introduced for the two thin plates. Then the dynamic model is established to study the dynamic behaviors of the composite flexible structure with various parameters. The results show that the nonlinear deformation appears obviously when the flexible composite plate structure is driven by various voltages, and the warping deformation becomes more obvious with the increase of the voltage. The width and thickness of the driven thin plate influence the stability of the whole structure. With the decrease of the width or thickness, the deformation of the structure is more consistent with obvious periodicity, and the control performance is improved. Finally, the structural parameters of the composite structures are optimized to improve the control performance based on the dynamic performance. Additionally, smaller width and thickness parameters are preferred to obtain better performance in the design of flexible actuator of soft robot.

Key words: flexible composite structure, absolute nodal coordinate formulation, dynamic behavior, deformation compatibility, optimal design

摘要： 介电弹性体与柔性材料的复合结构是软体机器人驱动器的主要形式，但柔性驱动复合结构的材料非线性与大变形行为导致其理论模型难以获得。本文基于绝对节点坐标法推导了薄板接触界面处的协调变形条件，引入薄板的超弹性本构模型和介电弹性体本构模型，建立了考虑柔性大变形的介电弹性驱动柔性复合板结构的动力学模型。研究不同驱动电压和结构参数下的柔性驱动复合单元的动力学特性，结果表明柔性驱动复合结构在电压驱动下产生明显的非线性变形，且电压越高翘曲变形越明显；驱动单元的宽度和厚度影响整个结构的稳定性，宽度和厚度较小时结构末端变形更一致且具有稳定的周期性，控制性能更好。基于动态特性对柔性驱动复合结构进行结构参数优化从而提高控制性能；针对软体机器人的柔性驱动器，优选更小的宽度和厚度参数可以获得更优的性能。

关键词: 柔性复合结构，绝对节点坐标法，动力学特性，变形协调，优化设计