Design Of DSP-based SPM Controller With Self-adjusting PI Parameters

Nanotechnology and its related research fields have been developing in the world. As we know, nanoscale detection is important and indispensable in the field. Scanning probe microscope (SPM), including atomic force microscope (AFM) and scanning tunneling microscope (STM), is a useful tool in exploring the world of nanotechnology.SPM is a series of instruments forming the image by different interaction between special probe and sample. A sensitive feedback control system is needed in SPM when detecting the sample surface. PID control technology is widely used in the scanning control system of traditional SPM. And PID parameters are adjusted by the operators manually according to their experiences and judgment of the image quality. Therefore, regulation of PID parameters in SPM is manual, low efficient and time-consuming.In this paper, based on theoretical research of the method of Scanning Parameters Optimization, a new DSP-based SPM controller with self-adjusting PI parameters is developed. The controller can calculate PI parameters in a short period of time and obtain the optimal parameters automatically. Experiments showed that it simplifies the process of setting parameters. Besides its advantages, such as saving time and labor, high automatic level, the controller can improve the image quality of SPM effectively. All of the work in the paper provides a solid foundation for operating SPM automatically.