Research On Control Theory And System Of Environment For Micro/Nano-meter Measurement

It's necessary to keep a high precision measurement environment of constant temperature, constant humidity, clean and anti-vibration for the field of micro/nano-meter measurement and control. Accurately controlling the environment is the basis to achieve the high-precision measurement. Many research organizations have concentrated on the research of micro/nano-meter measurement environment in the world. Some of the researches place the micro/nano-meter measurement equipment and device in the room of constant temperature, constant humidity and clean conditions. The operators, therefore, work in the room too. Actually only the measuring equipment needs the well-controlled measurement environment. Therefore, it's important in science and engineering to research a small measurement chamber of constant temperature, constant humidity, clean and anti-vibration measurement environment for micro/nano-meter measurement equipment.This thesis mainly focuses on the design and implementation of working principles and control system of measurement environment for micro/nano-meter measurement instrumentation. A high precision measurement chamber containing constant temperature, constant humidity, clean and anti-vibration conditions has been developed. The anticipated specifications are: temperature control with 20℃±0.05℃, relative humidity within 50%±2%RH, vibration less than 10μm/s, and the cleanness between 1000~10000 degrees.The key points of the thesis are as follows:(1) Research on a high accurate temperature measurement and control system To control the measurement temperature in a high precision level with the fluctuation less than±0.05℃using semiconductor refrigeration technology, this work studies the working principles and high accurate temperature closed-loop control technology of the system. The PID controlling algorithm is mainly studied, and the pros and cons of different kinds of PID algorithm are analyzed. Using the fuzzy deduction into the PID strategy, this work has successfully established the self-adapting PID control strategy technology. The simulation experiments on different kinds of control algorithm are based on MATLAB. The simulation results show that the fuzzy self-adapting PID control algorithm can meet the requirements of the specifications of temperature controlling system.(2) Research on the organization of the air flow and the structural optimization of the environmental control chamberThe organization of the air flow in the chamber is crucial for the balance of temperature field. Therefore, according to the researches on the air flow modes and the structural optimization of the environmental control chamber systematically, this work employs the methods of numerical analysis and CFD simulation to design a constant temperature and humidity chamber composed of three separated functrional chambers. Not only can the dynamic balance of temperature be achieved by effectively organizing the constant temperature air flow in the chamber, but also the partial thermal resource in the chamber can be separated to balance the temperature field. All these methods can be used to meet the precision of temperature control and uniformity index.(3) Research on anti-vibration and vibration isolation of measuring environmentIn order to eliminate the influences of environmental vibration on the high precision micro/nano-meter measurement, the mechanism of vibration isolation has been studied in the thesis. A solution of the vibration isolation is proposed and a two-stage passive vibration isolation system is designed. Its isolation capability has been theoretically analyzed and experimentally tested. The results show that the system reaches the design requirements.(4) Research on control method and integrated control systemThe multi-purpose integrated control system based on PC is researched and developed in this thesis. The temperature measurement and control system consists of a TEC (Thermoelectric Cooler), a programmable power supply and a precise temperature measurement system. Using the system identification theory and system identification toolkit of MATLAB, the mathematic model of the constant temperature chamber is identified. The best control strategy of the system is obtained by simulating a variety of control methods online. The program of the system is worked out by MATALAB embedded LabVIEW programming. By compensating the environmental factors in real time, the chamber temperature, humidity and air volume control are realized. The research meets the requirements of intelligent measurement and control.Research work and experimental results show that the constant temperature, constant humidity, clean and anti-vibration measurement environment of the micro/nano-meter measurement control chamber designed in this thesis meets the expected specifications.