| Inductive displacement transducers are playing a more and more important role in the field of ultra precision measurement. Inductive displacement transducers have become an essential sensor in the measurement of roundness or cylinder. The measuring precision of the inductive displacement transducers directly restricts the precision of the cylindrical measuring instrument. It has become the main bottleneck that limits the development of roundness and cylindrical measuring technique in our country. In order to ensure the measurement precision of the inductive displacement transducer for cylindrical measuring instrument, the inductive displacement transducer must be calibrated regularly. Generally, the measuring process of roundness and cylindrical is a dynamic process. Thus, there is an urgent need for an equipment that can calibrate the dynamic-static performance of inductive displacement transducer. Therefore, a sort of inductive displacement transducer calibration equipment, which can be used to automatically calibrate the dynamic-static performance of inductive displacement transducer, is designed in this paper.Firstly, this paper analyzes the present research status on displacement sensors calibration equipment and long stroke and high precision positioning platform at home and abroad. The macro and micro structure of the calibration device designed in this paper is determined. In order to ensure the dynamic performance of micro positioning platform, the load structure of micro positioning platform is analyzed by utilizing ANSYS finite element software to determine the optimal structure of the weight reduction. The first order natural frequency of the load structure after weight reduction is 1887.4Hz. The maximum deformation of the load structure is 0.39 nm in the high frequency motion state when the motion amplitude is 0.1μm and the motion frequency is 200 Hz.Secondly, the error analysis of calibration device is carried out. The influence of error sources on the system accuracy is analyzed. Analysis results show that the maximum error is Abbe error resulting from the yaw motion of macro positioning platform. Thus, double frequency laser interferometer is introduced to monitor the motion state of calibration device in real-time. The yaw angle in the process of motion is measured and compensate for it.Furthermore, The control scheme of calibration device is introduced. This paper presents two control strategies of macro and micro structure. The characteristics of the two control strategies are deduced and analyzed by the theoretical model. The modeling and simulation of control strategies were completed by Matlab/ Simulink. Considering the theoretical model and simulation results, the control strategy of macro motion following micro motion is chosen to realize the motion control of the calibration device.Finally, the experimental system of calibration device is set up and the performance of calibration device is tested. Test results show that the stroke of calibration device is up to 20 mm, the resolution of calibration device is better than 5nm, the linearity of calibration device is 0.000011%, and the repeatability of calibration device is 10 nm. The dynamic frequency is up to 100 Hz when the motion amplitude of calibration device is 0.05 mm. When the motion amplitude of calibration device is increased to 2mm, the frequency is decreased to 5Hz. Then the static and dynamic calibration experiment of the inductive displacement transducer for cylindrical measuring instrument is carried out. The experimental results show that the calibration device has the ability of dynamic and static calibration. Ultimately, the uncertainty analysis of the calibration device was carried out. The basic error of the calibrated inductive displacement transducer is ?=(510±31)nm(k=2). |
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