Study On Feedback Control Technology For Nano-Positioning

With the arrival of a new era of the nano-technology, tiny displacement and little geometry measurement have entered the scale of nanometer, even angstrom order. At the same time, development of modern precision machining technology request for the displacement measurement can reach high-resolution and precision on the wide range. So research on new nano-positioning and control technology has become an urgent requirement for many advanced technology.In the lab environment, disturbances originating from sound waves, vibrations, temperature variations, and other factors affect the SPM operational reliability. To solve the problem of the SPM equipments vulnerable to these interference, high-precision positioning nanotechnology is studied. A detailed analysis on the characteristics of nano-measurement and feedback control under the scanning tunneling state of STM system is made, signal acquisition and control hardware circuit and the suitable feedback control methods are designed. And the goal is to improve nano-positioning accuracy.The main research topics include:1. Get the deep understand on the content and development situation of nano-positioning technology. Taking the feedback control methods based on the tunneling effect as the typical application, the effective nano-positioning technology is studied.2. Design the feedback control experimental device model,which ensured the stability of the nano-positioning under the tunneling state with on-line control.3. For the nano-precision positioning requirements, the signal acquisition and control hardware circuit based on the DSP are designed. TI's floating-point DSP work as the center processing unit, through a CPLD logic control configuration, control the 18 AD, 20 DA, external memory components, and make the whole system working compatible.4. The control algorithm research aim at PZT micro-distance working table, compared the advantages on traditional digital PID algorithm,and fuzzy control algorithm. Simulation and analysis of the different parameters are carried out in Matlab. 5. To realize the feedback control, experiments use digital incremental PI algorithm are carried out. The results show that the experimental instrument can response to the displacement less than 1 nm, and real-time compensate for the interference is made, which has a better effect than the open loop measurement system. The source of the system interference is analyzed and the improved and settling method is put forward. All of these lay the foundation for the futher study of nano-positioning technology.