Study Of A Two-dimensional Nano-positioning System Combined With A Capacitive Displacement Sensor

In recent years, with the development of the machine-manufacturing, measurement science and material science, the precise positioning technology, as one of the key technology of precision engineering and precision apparatus, has already entered "nanometer" era. Nano-positioning systems have widely been applied into many fields, such as micro-electric technique, optical engineering, MEMS manufacturing and assembling, bioengineering and high accuracy basics measurement, and so on. A small two-dimensional nano-positioning system is designed and developed based on the requirement of weak-force measurement. Two piezoelectric actuators drive a cross-blade beryllium-copper flexure stage, and a two-dimensional capacitance sensor with stray-immune design is used as length standard to monitor the motion of the two-dimensional nano-positioning stage. A PID controller of incomplete differential and separating integral arithmetic is developed with Labview program, and it is used to control the motion of the piezoelectric actuators. The hysteresis and nonlinearity of the piezoelectric actuators are dramatically overcame by means of close-loop control, and the system can realize any planar trajectory within a range of 0.5μm×0.5μm, such as triangle, square, pentagon, hexagon and so on, their positioning precise can be controlled in 1nm. The system will be further improved so that it can satisfy the requirement of sub-micrometer precise positioning in weak-force experiments.