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

本课题的研究目标是研制一种工作范围达10 mm量级的粗、精加工机构系统，实现10 mm量级的亚纳米级加工和测量。在本课题中，首先，我们制作了一个由粗、细两部分组成的实验亚纳米机构，并对该机构进行了建模，然后讨论了该机构的最佳控制方法。选择了PID、模糊、神经网络和线性二次型控制方法，讨论了最佳控制方法。为了评价这些控制方法，确定了基本控制设计的规格，并从理论和实验上研究了定位系统及其控制器的鲁棒性。结果表明：（1）基于PID算法的亚纳米机构控制器满足控制设计指标，对台阶高度变化具有较好的鲁棒性。(2)基于模糊控制算法的控制器对动平台重量的变化和恒载荷的增加具有良好的鲁棒性，满足了设计要求。(3)在基于神经网络算法的控制器中，通过反向传播算法改变神经元的数目和权值的种类对系统的性能有影响。在实验中，为了保证高精度定位，需要限制权值的变化次数。(4)针对精定位机构设计的线性二次型控制器虽然能够实现对工作台的精确控制，但粗、精定位机构的控制器会使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.