| From of old, improving the diameter measurement accuracy of cylinder is a classical problem in the field of manufacture. Since the first cylinder was made, it has been the goal, which the craftsman and the engineer eager after from beginning to end, to find the better way of diameter measurement and to make these measurements more and more precise. Nowadays, with the rapid development of the military and aerospace technology, the demands of large dimension and high accuracy in cylinder manufacture is becoming more and more important. No ultra-precision measurement, no ultra-precision manufacture. The work described in the dissertation is researched under this background. The dissertation focuses on the key theory, method and techniques of improving the cylinderdiameter measurement accuracy. The main research concerns on the following lists: 1 , Compared with existing devices and principles of the cylinder diameter measurement, a new optical scanning measure diameter mathematical model is built, which is based on geometrical optics approach. The relationship of sensibility and spot size is analyzed. And the multipurpose theoretical model is used in edge checkout methods include laser half-focus method, Zero-pass method and extremum method. In CCD scanning method, the image edge checkout model and the pixel subdivision is established based on the principle of image edge identify. 2, A new displacement forecast model in search of character point on cylinder edge is first time established. The model is based on BP neural network and the parameter model of the cylinder which under detect.3, Based on golden section optimal method, the localization strategy of ultra-precision cylinder edge checkout is proposed in small measurement range. By combination golden section method and BP neural network forecasting, the optimal localization strategy is established in cylinder full measurement range. The efficiency of cylinder diameter measurement is greatly improved.4, Through study of coordinate relationship between measurement probe and workpiece, the localization error of ultra-precision measurement mechanical is attained based on coordinate transform method.5, The mathematical model of measurement error is established . The influence of the probe structure parameter, component design error and mechanical fixing error is all considered in this model. Then, the numerical simulation is fulfilled, along with a series of rules of the influence on precision measurement caused by probe parameter and the relative position between probe and workpiece.6, Based on Hertz elastic theory, the deformation model of workpiece caused by touch force isestablished. And the numerical simulation is also fulfilled, along with a series of rules of the influence on contact property caused by the characteristic parameters of probe and workpiece. Then the deformation error caused by touch force can be compensated in the last result. 7, A novel linear DC electromagnetism actuator(LDEMA) for ultra-precise contact probe positioning is proposed. The electromagnetism character of LDEMA is analysed by using FEM method. On the basis of electromagnetism theory, ihe transfer function between displacement and controlled parameters of LDEMA system is obtained. Meanwhile, a kinetic mathematical model of motion characteristic for LDEMA system is studied in this dissertation. The paper also brings forward a hybrid control method of Fuzzy-PID, which resolve perfectly the problem of response's delay and the fuzzy positioning value of LDEMA. 8 , A novel instrument that can attain ultra-precision for measuring diameter of cylinder is presented. The instrument is designed on the basis of Abyi principle and the techniques researched in this dissertation, such as LDEMA, Fuzzy-PID control, air-lubricated hydrostatic slide guide and contact error compensation. The instrument measurement precision is on top of the diameter measurement field.9, The affection of vibration and temperature is also considered. Relevant controlling method is proposed...
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