Nano-CMM Control Based On LabVIEW

A software system for nano-CMM is proposed in this paper. Control method of every part of the nano-CMM and measuring software of some new sensors have been developed.In this study the expected measuring range of the nano-CMM is 20mm X 20mm ×10mm. In this system a Linear Linear Diffraction Grating Interferometer (LDGI) is developed as displacement sensor and DVD pick-up head is structured on the end of Z axis.In this study the software system is worked out based on the graphic language LabVIEW. The main work includes: acquisition and process of LDGI signals, pulse counting and signal subdiviation, calculation of displacement, positioning control of the XY table, control and data correction of DVD pick-up head, process of the data and some typical application of the system.In this measuring system, the motion control strategy is of great significance. The motion velocity should be stable and low. A control diagram based on classic PID control and back-propagation neural network (BPNN) is proposed. Three driving modes of different velocity and resolution (AC mode, GATE mode and DC mode) are used to realize both long stroke length and high resolution.The main errors of the nano-CMM are analyzed in this paper and some improving methods are proposed.The performance of the software has been tested by experiments. The stage can move of a stable and low velocity and measuring and positioning repeatability have been achieved to 30nm. After positioning correction of DVD pick-up head measuring repeatability of Z axis can reach 20nm.