Nano Coordinate Measuring System Based on the 3D Tactile Probe
|Keywords||Complex surface Nano coordinate measurement 3D tactile probe Probe calibration Form measurement|
The development of ultra-precision manufacture requires more advanced measuring methods. In particular, high precision measurement of small aspheric and free form surface becomes a research focus throughout the world. With the superiorities in accuracy, efficiency, versatility and real 3D measurement, nano-CMM has been a new method for small complex surface testing. This dissertation described a 3D coordinate measuring system based on 3D tactile probe and nano measuring machine (NMM) which is capable of testing small complex surface with nanometer resolution. The main achievements in this dissertation are as follows:(1) A systematic introduction of the development of nano-CMM and 3D tactile probe, laboratory equipment in national metrology institutes and products in the market, was given in this dissertation.(2) A nano coordinate measuring system was built up by studying data processing algorithms and CMM system theory, which using 3D tactile probe (Gannen XM) and nano measuring machine (NMM) as the main components. The probe is based on piezoresisitive effect with the measuring force less than 1mN and the 3D uncertainty is 50 nm. The NMM has the measuring range of 25 mm×25 mm×5 mm with the resolution of 0.1 nm. A signal acquisition module NI-USB6259BNC was used to acquire the signal of the probe and the feedback system was based on its analog output function. Illumination, observation and temperature control components were used in this measuring system. And the control and data processing software was designed.(3) The performance of the probe and measuring system was analyzed. After analyzing, the linear error was calculated as 0.6% and the hysteresis was 0.24%; the test carried on a inclined surface showed that the spatial displacement was better than the Z axis displacement to be employed in the feedback system; the transformation matrix obtained from the probe’s calibration, which transformed the voltage signal into the displacement signal, was tested to prove its reliability.(4) The performance of the measuring system was tested by measuring some typical samples. Measurements of step height, flatness, cylinder diameter, complex surface, were designed for analyzing the errors of the measuring system. The results certify that the proposed system based on 3D tactile probe is an effective method of measuring small complex surface.