Study on Measurement and Control of Dynamic Behavior of Subnano-mechanism

本课题的研究目标是开发具有10毫米量级长工作范围和亚纳米级以上高定位分辨率的粗细机构系统，实现10毫米量级的亚纳米级加工和测量。本课题首先建立了由粗机构和细机构组成的实验亚纳米机构，并对其进行了建模，探讨了该机构的最佳拟合控制方法。选择PID、模糊控制、神经网络和线性二次控制方法进行了最优拟合的讨论。为了评估这些控制方法，确定了基本控制设计规范，并对定位系统及其控制器的鲁棒性进行了理论和实验检验。结果如下：(1)基于PID算法的亚纳米机构控制器满足控制设计要求，对阶跃高度的变化具有良好的鲁棒性。(2)基于模糊算法的机构控制器满足设计要求，对活动台面重量变化和恒定载荷的增加具有良好的鲁棒性。(3)对于基于神经网络算法的控制器，反向传播算法改变的神经元权值的数量和种类对系统性能有影响。在实验中，对重量变化次数的限制是实现高精度定位的必要条件。(4)虽然为精细定位机构设计的线性二次型控制器可以对工作台进行精确控制，但对于粗、精定位机构的控制器会使其工作台在参考位置附近产生振动。

The aim of this research project was to develop the coarse and fine mechanism system with a long working range on the order of 10 millimeters and high positioning resolution for realize more than sub-nanometers for realize sub-nanometer machining and measuring on the order of 10 millimeters. In the project, first, the experimental sub-nanomechanism which consists of the coarse and the fine mechaisms was made and modeled for the aim and then the best fit control methods for the mechanism were discussed. PID,Fuzzy, Neural network and Linear quadratic control method were selected for the discussion of the best fit one. In order to evaluate these control method, the specification of basic control design was determined and the robustness of the positioning systems with their controller were examined theoretically and experimentally. The results were the following ;(1) The controller based on PID algorithm for the sub-nanometer mechanism was satisfied the specification of the control design and had the good robustness to the change of the step height.(2) The controller based on Fuzzy algorithm for the mechanism was satisfied the specification and the good robustness to the change of the weight of the movable table and the addition of the constant load.(3) In case of the controller based on Neural network algorithm, the number and the kind of the weight of the neuron changed by the back propagation algorithm influenced on the performance of the system. In the experiments, the limit of the number of the weight changed is necessary for high precision positioning.(4) Though the linear quadratic controller designed for the fine positioning mechanism can control the table precisely, the controller for the coarse and fine positioning mechanism causes the vibration of its table near the reference position.