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类型 基础研究 预答辩日期 2018-03-12
开始(开题)日期 2016-10-28 论文结束日期 2017-11-27
地点 东南大学机械楼327 论文选题来源 国际合作研究项目    论文字数 5.7 (万字)
题目 基于软驱动器的软体飞行器的研究
主题词 相变转换,介电弹性体,圆形支撑框架,DE球体,大变形
摘要 航空法规定直升机不能在一定的高度(0~300米)范围内飞行,而地面上所发生的自然灾害,植被状况等信息需要方便快捷地从空中观测和拍摄,所以研究设计近地面可控飞行的设备成为了迫切需求,尤其是对自然灾害频发的区域,农场等地点。无线可控氦气球体系统,具有可携带重物多,续航能力强等特点,同时也是低成本、低噪音、快速、节能、安全和可靠的新型航空观测工具。尽管目前在软体驱动器机理及仿生应用的研究方面已经取得了阶段性进展,但对于软驱动飞行器的飞行机理的认识尚不充分。因此,深入了解软驱动飞行器的合理结构及运动规律,开展软驱动器及飞行应用方面的理论、仿真计算及实验研究,对运动中的受力及功耗等关键问题进行分析,有助于加深对软飞行机器人飞行机理的认识,为将来软驱动飞行器的的研制提供参考。 本文在软球体驱动器的基础上,研制了可实现上升下降、旋转、平移运动的飞行机器人,并建立了相关参数的计算模型,通过观察测量、实验、理论推导、仿真计算等研究了参数变化对机器人升力、阻力及运动轨迹等问题的影响。本文主要研究内容及结论如下: (1) 对于具有机电性能和承载能力的球体驱动器尺寸结构和体积变化规律研究。搭建了软球体驱动器信息采集实验平台,使用高速相机采集软DE球体变形信息,经软件分析及计算后获取了体积与压力等参数的关键数据。基于所设计的结构和得到的数据,建立了软驱动飞行机器人系统,推导了实时变化的预拉伸率、电压、压强、电荷及体积的计算公式。对于球体驱动器,根据弹性体材料的Helmholtz自由能可以计算出电压与DE膜预拉伸的关系,DE膜自由能的变化与电压、压力和惯性力所做的功有关,结合系统的Maxwell应力,得出关键参数之间的关系式模型。在电场力作用下,DE薄膜上存在着机电不稳定和电击穿现象,电击穿场强与材料的拉伸值密切有关,随着电压的增高,机电不稳定性产生,褶皱一般在球体密封口边缘形成,为条形状直到电击穿发生,出现该现象的结构预拉伸系数λpre范围为3~6,电压Ф≥5.5 kV。 (2) 对于实验过程中DE膜表面存在的不稳定现象,比如loss of tension和电击穿的研究。电压所引起的软材料介电弹性体上的相变转换,可以用来模仿生物的附着功能和表面皮肤的纹理。圆形DE膜上涂有电极区域在电压作用下所呈现的平坦、褶皱或者膨胀凸起的状态,验证了理论关于相变转换与失效现象的预测。当介电弹性体膜受到径向力和逐渐递增的电压时,四种试验现象发生在介电失效之前:膜上涂电极区域的区域向无电极区域扩张,但是DE膜依然平坦;膜上仅仅产生膨胀凸起状态;膜上膨胀凸起部分与褶皱部分共存;涂有电极区域完全转换为褶皱状态。在第四种现象中,膜表面上的平坦区域和皱纹区域存在着两种不同类型的转换:褶皱在平面膜上小区域形成,然后蔓延至整个涂电极区域,该过程是连续的相变转换;随着电压的升高,皱纹和平坦区域相互转换直到电击穿发生,该过程是跳跃式的相变转换。研究发现预拉伸对介电弹性体的机电相变有着显著的影响。 (3) 可实现大变形的介电弹性体软球体驱动器的结构设计。当球壳在厚度方向受到电场作用时,DE球膜在径向方向扩张,在厚度方向变薄。在DE球体实验平台上,采用压力和位移传感器测量球体的变化。研究了软球壳的扩张幅度、频率等参数变化对升力、阻力及运动方向的影响。基于理论分析,设计了一些球体结构,内部充满氦气或者空气;实验主要结论包括:在相同的压力下,DE氦气球的体积小于空气球体积;用于实现控制的大变形对于软驱动飞行器非常重要,具体方法可以增大初始体积、电极密度和预加载等以达到软驱动器大变形的目标;体积值变化越大,可以控制的氦气球飞行高度越高,可控制的质量越多,基本呈非线性增长关系;通过对预拉伸球壳的动态行为的分析,得出DE膜较厚的球壳比薄球壳变形小;最后,大量的实验证明了DE氦气球载物可控飞行的可行性。 (4) 基于软球体驱动器,研究软体机器人升力、阻力及功耗等问题。在理论研究方面,基于所设计的DE球体驱动器,建立了软体机器人的计算模型;通过对球膜的受力分析,计算得出了系统质量、速度、加速度等参数。利用Gent模型推导出了体积与压力关系方程,并结合理想气体状态方程,得出了临界击穿电压与预拉伸半径之间的关系;在仿真计算方面,研究了DE球体内部乳胶破裂时,VHB球体的变化趋势,并对变化趋势及原因进行了分析;在计算结果与实验结果的比较方面,分析了直流电大小、交流电幅度、频率等参数对机器人运动方向的影响。理论推导、实验及计算结果均表明,乳胶球膜的击穿电压范围一般在1.5~5.5 kV之间,大多集中在2.5 kV左右,与膜的厚度有关。在内部乳胶球破裂瞬间,介电弹性膜球体产生相对较大的体积扩张,机器人系统产生上升的浮力和加速度,随后在空中会受到来自空气和风的阻力,以及不同高度的压强变化等因素的影响而停留在一定的高度浮动。 (5) DE驱动机器人的可控的上升、下降、旋转和平移飞行。考虑到实际的软驱动飞行机器人的结构尺寸对于运动的影响,建立了电压、预拉伸和体积计算模型。对机器人的运动轨迹进行了分析,实验结果验证了计算模型的准确性。结合惯性功耗对机器人在直流以及交流电压作用下的运动方向进行了分析,表明了转变设计结构,机器人能够实现无在线控制条件下的转动和平移等运动。统计了飞行运动中体积所能达到极限值及平均值等。通过计算飞行中球体的体积变化,得出飞行加速度。给DE驱动器连通大的无弹力腔体,使得DE驱动飞行机器人可控飞行,也可以搭载无线控制系统和载荷飞行;为了实现系统的控制策略,协调各个控制器,提出了将中心主控制器和软驱动控制器,尾翼等部分看成独立的智能体,确定了各部分之间的通信和协作机制;制定了信息交流格式,并对软件设计流程做了说明。另外,机器人可控的浮力随着飞行高度的增加而减小,随着温度的升高而降低,也会随着大气中湿度的增加而降低。
英文题目 Research on software air vehicles based on soft actuators
英文主题词 Phase transition,Dielectric elastomer, Circular frame, DE balloon, larger deformation
英文摘要 The helicopter cannot fly at the height from 0 to 300 m by the aviation law, natural disasters and vegetation information on the ground need to be observed and photographed from the air conveniently, controllable flight devices close to the ground are demanded urgently. Wireless controllable helium balloon system has characteristics of carrying heavy things, long battery life, low cost and noise, fast, energy saving and safe. Although some progress has been made on the bionics application, the understanding of the flight mechanism of robots based on dielectric elastomer actuators (DEA) is not sufficient. Therefore, design the reasonable structures and movement rules, carry out theoretical computation and experimental research, analyze the force, power and other key issues for the robot motion, all which will help to develop the flight mechanism and provide references for the soft-drive vehicles in the future. The flight robot base on DEA could realize the up and down, rotational and translational motion, calculation models were established, the influence factors on the buoyancy, the resistance and the trajectory were studied through measurements, experiments, theoretical derivation and simulation. The main contents and conclusions are as follows: (1) Study on the reasonable structure and volume change of balloon actuators with electromechanical properties and carrying capacity. An information collection platform was built, meanwhile, high-speed cameras were used, the critical data of parameters was obtained after the software analysis and calculation. A flying robot system based on DEA was established using obtained data; Formulas were derived to describe real-time variations of pretension, voltage, pressure, charge and volume. The variation of the Helmholtz free energy equals the work done by voltage, pressure and the inertia, combining with the Maxwell stress, models with key parameters are obtained. Under the effect of electric field exists the electromechanical instability and electric breakdown phenomena on the DE film, electric breakdown relates to the prestretch closely, with increasing voltage, the electromechanical instability happened, wrinkles formed either near the clamped edge or the top part in the inflated balloon whose pre-stretch coefficient λpre was 3 to 6, the voltage Φ was greater than 5.5 kV. (2) Unstable phenomena on the DE surface, such as loss of tension and electric breakdown. In order to imitate biological adhesion performance and skin properties, dielectric elastomers applied high voltages are used. A DE membrane could undergo wrinkles or bulging from the flat state when a critical voltage is applied. Parameters of the theory were obtained by fitting the experimental records. Four experimental phenomena were found out before electric breakdown in membranes supported by a circular frame: The active region in a membrane expanded against the passive region, the membrane was still flat till breakdown; Bulging formed on the membrane; Wrinkles and bulging coexisted; Wrinkles formed without bulging; Additionally, in the fourth state, two types of transition between flat regions and wrinkled regions were observed: Wrinkles formed in small regions, then they grew at the expense of flat regions until the entire active region became wrinkled, the process was continuous; Both wrinkled and flat regions moved interchangeably on the membrane till breakdown. It is found that the prestretch affects electromechanical phase transitions significantly. (3) The structural design of the DE balloon actuators with large deformation . When the DE spherical shell is subject to an electric field through its thickness, it expands in radial direction and contracts in thickness. On the experimental platform, the pressure and displacement sensors were used to measure DE balloons. The influence of parameters, such as expansion amplitude and vibration frequency of soft spherical shells, was presented and analyzed on the buoyancy, the resistance and movements. Based on theoretical analysis, some spherical structures filling with helium or air are designed. The main conclusions of these studies include: Under the same pressure, the volume of the DE helium balloon is smaller than air balloon; The large deformation is very important for controlling DEA robots, we can increase the initial volume, electrode density and preloading to achieve this aim. The greater volume changes, the more weight can be taken by a helium balloon, and the more buoyancy force could be controlled. By analyzing the dynamic behavior of spherical shells, the thick ones deformed smaller than thin shells. Finally, A large number of experiments demonstrated the feasibility of the controllable flight for the DEA robot. (4) Based on DE balloon actuators, the buoyancy,the resistance and power consumption of the robot were studied. Computational models of the DEA robot were established. The quality, speed, acceleration and other parameters of the system were calculated out. The relation between the critical breakdown voltage and the prestretching radius were obtained which explored the Gent model to derive the equation of volume and pressure combining the ideal gas law. The simulation was given to describe the change trend while the natural rubber coupled with VHB. Compared with experiments, the influence of the parameters, such as DC voltage, AC amplitudes, frequency, was analyzed on the moving direction of the robot. The breakdown voltage range of natural rubbers is generally between 1.5 kV and 5.5 kV, mostly at about 2.5 kV, which relates to the thickness of rubber. When inner rubber is blast, the volume change of the DE balloon is relatively giant, therefore, the buoyancy and acceleration of the DEA system are produced, the soft-driven robot will stay at a certain level in the sky. (5) The controllable up-and-down, rotating and translational movement of the DE actuated robot. Considering the actual structure effect on robot motion, models of voltage, pretension and volume were established. The moving trajectory was analyzed, and experimental results verified the accuracy of the models. Combined with inertial power consumption, moving directions were analyzed under the effect of DC and AC voltage, the robot can realize wireless control in rotational and translational motions, etc. The DE balloon actuator was connected to a large and non-elastic chamber with carrying wireless controlling system and loads. The flight acceleration was obtained by calculating the system volume change. In order to realize the controlling strategy and coordinate each controller, we put forward the main controller, soft actuated controller and the tail part as independent agents, the mechanism of communication and collaboration between each part were given; The information exchange format was developed, and the software design process was explained. In addition, the controllable buoyancy of the robot decreases with the increase of flight height, the temperature and the humidity in the atmosphere.
学术讨论
主办单位时间地点报告人报告主题
东南大学 2013.10 东南大学机械楼 吴闻宇 高速列车座椅特征因子提取及静态坐压舒适度研究
东南大学 2013.10 东南大学机械楼 Prof. Fengjun Yan Modeling, Estimation, and Control on Advanced Combustion Diesel Engines
东南大学 2014.04 东南大学机械楼 Prof. Jianbo Gao Complex systems and emergence: How theory meets reality
东南大学 2014.06 东南大学教学楼4 Prof. Lin Ma Advanced research in integrated engineering asset management
东南大学 2014.06 东南大学机械楼 奥川雅之 副教授 智能机械与建筑安全
新加坡国立大学 2015.02 机械系E2 张慧 Phase transitions on dielectric elastomers
新加坡国立大学 2016.05 机械系E2 张慧 Spherical actuators based on dielectric elastomers
东南大学 2016.12 东南大学机械楼 张慧 软球体驱动器无线控制
东南大学 2017.04 东南大学机械楼 张慧 软机器人飞行原理
     
学术会议
会议名称时间地点本人报告本人报告题目
M2VIP2016 2016.11 东南大学
ICIT2017 2017.03 加拿大 Balloon actuators based on the dielectric elastomer
M2VIP2017 2017.11 新西兰 Dynamic Patterns on a Circular Dielectric Elastomer Thin Film
     
代表作
论文名称
Harnessing dielectric breakdown of dielectric elastomer to achieve large actuation
Balloon actuators based on the dielectric elastomer
 
答辩委员会组成信息
姓名职称导师类别工作单位是否主席备注
帅立国 正高 教授 博导 东南大学
李东波 正高 教授 博导 南京理工大学
殷晨波 正高 教授 博导 南京工业大学
毕可东 正高 教授 博导 东南大学
幸研 正高 博导 东南大学
      
答辩秘书信息
姓名职称工作单位备注
戴敏 副高 副教授 东南大学