Xue Shuqi, Dong Wenbo, Chen Dongyang, Guo Qingyuan, He Huan, Yu Jianding
Key Laboratory of Space Utilization, Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences, No. 9 Dengzhuang South Road, Haidian District, Beijing 100094, China.
State Key Laboratory of High-Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, No. 1295 Dingxi Road, Changning District, Shanghai 200050, China.
Rev Sci Instrum. 2021 Jun 1;92(6):065111. doi: 10.1063/5.0026974.
Electrostatic levitation is an important method of studying material properties. Without using a container, a physical object is levitated between electrostatic plates and melted to the liquid state using a laser. Then, measurements are made via fast cooling or oscillation. Control technology is critical to the electrostatic levitation system. Uncertainty regarding the sample charge during the start-up and laser-melting periods often causes disturbances or causes levitation to fail. In this paper, we design a two-step adaptive control strategy with charge estimation and feed-forward control. This method can better adapt to charge uncertainty during the initial stage. In addition, we propose an innovative new method of superimposing oscillation signals via software to measure the material surface tension and viscosity. Unlike the traditional method, this approach does not require extra hardware resources and is flexible with regard to regulating the frequency and amplitude. A control system model with an accurate electric field model is established and used to simulate control progress in order to illustrate the advantage of our control method. Experiments based on a high-speed vision-servo system also validate the effectiveness of the adaptive and oscillation control strategies.
静电悬浮是研究材料特性的一种重要方法。在不使用容器的情况下，将一个物理对象悬浮在静电板之间，并用激光将其熔化至液态。然后，通过快速冷却或振荡进行测量。控制技术对静电悬浮系统至关重要。在启动和激光熔化阶段，样品电荷的不确定性常常会引起干扰或导致悬浮失败。在本文中，我们设计了一种带有电荷估计和前馈控制的两步自适应控制策略。该方法能够更好地适应初始阶段的电荷不确定性。此外，我们提出了一种通过软件叠加振荡信号来测量材料表面张力和粘度的创新方法。与传统方法不同，这种方法不需要额外的硬件资源，并且在调节频率和幅度方面具有灵活性。建立了具有精确电场模型的控制系统模型，并用于模拟控制过程，以说明我们控制方法的优势。基于高速视觉伺服系统的实验也验证了自适应和振荡控制策略的有效性。
