Design of a Control System for Precision Two-Dimensional Positioning Platform of Small Desktop Scanning Electron Microscope

In this paper, a control system is designed for the precision two-dimensional positioning platform in small desktop scanning electron microscope. The positioning platform is driven by a stepper motor, and the control system contains control circuit and control program. RS485 protocol or Ethernet is adopted by the system to communicate with the host. The system realizes the functions of position closed-loop control, S-sharped speed curve control and error compensation for the stepper motor to achieve the target of easy operation with a stable, rapid and high-precision position. The experimental results show that the platform that adopted this control system could get the accuracy of the X-axis is
$\pm 7.88\mu \mathrm{m}$
, the repeated positioning accuracy of the X-axis is
$\pm 3.21 \mu\mathrm{m}$
, the positioning accuracy of the Y-axis is
$\pm 5.28\ \mu \mathrm{m}$
, and the repeated positioning accuracy of the Y-axis is
$\pm 4\ \mu \mathrm{m}$
, which meets the requirements of precision two-dimensional worktable in small desktop scanning electron microscope.