基于介电弹性体驱动器的软体机器人建模与跟踪控制

针对基于介电弹性体驱动器的软体机器人的跟踪控制问题,本文提出一种自适应鲁棒控制策略.根据虚功原理建立介电弹性体驱动器的动力学模型,模型中弹性势能部分采用Gent模型进行描述.考虑到介电弹性体驱动器的精确模型参数难以获取,使用基于径向基神经网络的逼近器对模型中的未知项进行估计.同时,考虑到介电弹性体驱动器形变量的变化率难以被测量,设计状态观测器对系统未知状态量进行观测.根据逼近器的估计结果和状态观测器的观测结果,设计滑模控制器实现介电弹性体驱动器的跟踪控制目标.最后,通过数值仿真实验验证所提控制策略的有效性.

介电弹性体驱动器动态电压下的变形特征及击穿行为研究

针对介电弹性体(DE)驱动器驱动性能难以预测的问题,以VHB4910薄膜为待测DE材料,圆形DE驱动器作为研究对象,针对低频条件下(0.1～10Hz)DE驱动器的动态变形与击穿行为展开了实验研究。搭建了力电耦合实验测试平台,通过实验归纳了驱动电压参数对DE驱动器动态变形和击穿的影响规律。实验结果表明:DE驱动器的动态变形平衡位置受到电压幅值的影响,动态变形的振幅则受到电压频率和幅值的共同制约。动态击穿电压的数值分散性强,难以得到明显的规律特征,因此不能准确对动态击穿行为进行表征,而通过实验发现DE驱动器能承受的电压循环周期数会受到多种驱动电压参数的显著影响,故提出采用电压循环周期数对动态击穿行为进行分析。借鉴机械循环载荷下的经典疲劳曲线方程,提出利用名义静电应力幅值代替机械应力幅值、对DE驱动器在动态电压下的电致疲劳寿命曲线进行拟合的方法,以期为动态电压作用下DE驱动器的寿命预测提供一种新思路。

MWCNT-CB/PDMS复合电极介电弹性体驱动器的制备与性能优化

介电弹性体驱动器(DEA)的柔性电极发挥着产生电场和约束介电母体形变的重要作用。本文以一维的多壁碳纳米管(MWCNT)和零维的导电炭黑(CB)为共同导电填料,设计浇注了一系列不同尺寸、不同力学、电学性能的聚二甲基硅氧烷(PDMS)复合电极膜(MWCNT-CB/PDMS)。将电极膜黏附在聚氯乙烯凝胶膜的两侧表面,导入脉冲高压电信号,获得一系列电驱动行为变化的新型介电聚合物驱动器。驱动性能测试结果表明:电极覆盖率的增加有利于DEA位移输出;电极厚度的增加限制了DEA的位移输出;随着MWCNT掺杂量的增加,位移输出先增后减。正交实验结果表明:MWCNT掺杂量对DEA的驱动位移有显著的影响,电极覆盖率和厚度有高度显著的影响;最优组合下,驱动器的最大位移输出为1.71 mm。

基于介电弹性体的软体机器人设计、建模与运动控制研究综述

软体机器人是一个多学科交叉的新兴领域,旨在基于软质材料开发类似自然生物的多功能系统,赋予机器人强大的环境适应性、优良的运动灵活性以及高效安全的人机交互能力。介电弹性体是一种新型的软质智能材料,具有弹性模量低、变形范围大、能量密度高、响应速度快等优点,适合于制作软体机器人。首先,介绍几类介电弹性体软体机器人。然后,总结介电弹性体驱动器动力学建模与控制的研究进展。最后,分析介电弹性体驱动器研究当前的挑战,并展望进一步研究的机遇。

Fabrication and stiffness optimization of carbon-based composite double polymer compliant electrode

A manufacturing method is proposed for carbon based composite double polymer compliant electrode.The stiffness of this compliant electrode is changed by adjusting the mass fraction of carbon black and the ratios between Ecoflex20 and RT625.Tensile machine is used to test its ductility and hardness.The conductivity is measured through the source table.Finally,it is printed on the dielectric elastomers(DE)film,and the high-voltage amplifier is used for dielectric elastomers actuators(DEAs)dynamics testing.The results show that the compliant electrode has high tensile properties(>200%),low stiffness(<300 kPa)and well conductivity(0.0493 S/cm).It is proved that the DEAs displacement output is up to 1.189 mm by this compliant electrode under dynamic response,which is 1.64 times and 1.32 times of the same type.Moreover,this formula extends the curing time of the original compliant electrode ink.It can provide a reference for the production of compliant electrode and DEAs in the future.

Analytical models for circular and spherical dielectric elastomers

In order to imitate skin characteristics, a dielectric elastomer (DE) membrane coated with flexible electrodes is applied with high voltage, which can lead to wrinkles and other phenomena. To develop soft-actuated air vehicles and other equipment, lightweight gas is pumped into a DE spherical shell to generate controllable flight movements. According to experimental phenomena and data, the calculation models of phase transitions on circular DE films are built. Meanwhile, the deformation characteristics of different DE (acrylic polymer and rubber) spherical actuators combined with helium are compared. The peak pressure inside a rubber balloon is greater than that of a VHB (acrylic polymer) balloon shell, but the limit stretch of rubber is much smaller. By taking advantages of this phenomenon, large deformations of a VHB spherical shell can be realized at an actuated state. Moreover, multi-layer spherical DE shells can achieve larger voltage-induced volume change than monolayer ones. The research indicates that pre-stretching is one of the key factors to induce phase transitions between flat, wrinkled and bulging regions on circular DE films, and the internal pressure determines the electromechanical performance of balloon actuators.

Homogeneous large deformation analysis of a dielectric elastomer peristaltic actuator

A series of isometric,radially expanding tubular units,made of dielectric elastomer with compliant electrodes,constitute a soft linear peristaltic pump with distributed actuation for transport of incompressible fluids.Based on the Gent strain energy model,this paper theoretically analyzes the homogeneous large deformation of the peristaltic unit.We discuss the effects of axial prestretch on the actuation of the actuator.We then predict the maximum actuation strain of this actuator which is limited by dielectric strength of the polymer.The results presented here extend the previous study based on linear elasticity,and can predict the electromechanical behaviors of the novel actuator at large deformations.

Failure modeling of folded dielectric elastomer actuator

When subjected to voltage,the dielectric elastomer membrane reduces its thickness and expands its area under the resulting compressive force.This characteristic enables the dielectric elastomer actuators of different structures to be designed and fabricated.By employing the thermodynamic theory and research method proposed by Suo et al.,an equilibrium equation of folded dielectric elastomer actuator with two generalized coordinates is established.The governing equations of failure models involving electromechanical instability,zero electric field,electrical breakdown,loss of tension,and rupture by stretch are also derived.The allowable areas of folded dielectric elastomer actuators are described.These results could provide a powerful guidance to the design and performance evaluation of the dielectric elastomer actuators.