Research On Synthetic Measurement System Of Profile With Large Range

With the rapid development of manufacture technologies, the synthetic measurement of profile with large range and high precision has become more and more imminent. However, so far most of contact profilometers can not be applied to synthetic measurement of profile with large range and high precision because of the contradiction that can not be reconcilable between measuring range and measurement accuracy. The non-linear measurement error, which can not be completely eliminated by compensation ways, as well as the measuring force of the lever-type stylus displacement sensor increases with the rise of measuring range.The synthetic measurement system of profile described in the present paper is different from traditional profilometer. It has solved the difficult problem that traditional profilometer can not attain high precision with large measuring range. So the synthetic measurement system of profile with large measuring range has wide application prospect.The creative points and main research contents are as follows:A synthetic measurement system of profile with large measuring range and high precision, which is based on the principle of zero position tracing, has been proposed and developed. On every sampling point, if the zero offset of the displacement sensor exceeds the preset threshold value, the measurement system will drive the vetical displacement platform to move vertically to ensure that the zero offset returns to the threshold value. The synthetic measurement system can realize synthetic measurement of profile with large range, high precision, small measuring force and high efficiency.A displacement sensor with double diffraction gratings is studied. Its principle, characteristic and non-linear measurement error is analysed. It has many advantages such as simple structure, reliable working, small volume, strong anti-interference ability, high resolution and small non-linear measurement error.A synthesis analysis method of non-linear measurement error of lever-type stylus displacement sensor is proposed. The analysis method divids the non-linear measurement error into front end non-linear error and back end non-linear error, then they are integrated into a error model by the turn angle of the lever. And the non-linear error compensation ways and its feasibility are discussed.A iteration calibrating algorithm of zero position of lever-type stylus displacement sensor is proposed. By means of the iteration operation, the zero position of the displacement sensor is close to its true value step by step. The iteration calibrating algorithm can find the zero position of the displacement sensor accurately, so the non-linear error caused by the lever-type stylus displacement sensor can be decreased farthest.A X-Y-Z metrological displacement platform is analysed. AC servo motor and double diffraction gratings metrology systems are adopted in X, Y and Z directions.A method of synthetic measurement data processing and evaluation is studied. The synthetic measurement system of profile with large measuring range has been applied to practice measurement. Some cases of measurement and evaluation have been gived.