A geometrical parameters precision measurement system based on machine vision is designed

the system is built on the mechanical platform of universal tool microscope.The machine vision and computer technology are utilized to achieve aided aim of border and line

the precision measuring of length

diameter and angle are realized by the grating measuring technology based on field-programmable gate array（FPGA） and single chip microprocessor（SCM）

the automatic acquisition and handling of data by programming the correlative software are completed

and the aided measuring of the part is implemented by combining with the AutoCAD software.The experimental results demonstrate that the system has high repeatability precision and measuring precision

due to that it not only keeps the universal tool microscope’s advantage

such as good stability

strong anti-jamming

but also has the capability of eliminating the personal error and improving the measuring efficiency.