Speed Measurement And Vibration Detection Of Translational Motion Based On Electrostatic Induction

In the process of modern industrial production, the mechanical devices become more sophisticated than ever. Speed measurement and vibration detection play a significant part in reliable operation of the equipments. Precice measurement of the running speed of mechinery can help to enhance the accuracy of manufacturing, while device failure can be predicted at early stage through vibration detection.Contact-type speed measuring instrument is error-prone and it is difficult to realize vibration detection with the same instrument. Most non-contact measuring methods can be applied to a variety of materials without interference, but it is expensive for them to achieve a higher accuracy. By collecting the electrostatic signals generated during the operation of an machinery, the operating condition of the equipment, including the speed and vibration can be monitored in an online, non-contact manner. The main contribution of this thesis is as follows:According to the principle of electrostatic induction and the characteristics of the electrostatic signal, this paper peoposed the method of using electrostatic sensor array for strip speed measurement. The upstream and downstream sensors signals were collected and the cross-correlation algorithm is adopt to get the transit time and correlation speed. To improve the accuracy and repeatability of the measurement system, the final strip speed of the speed measurement system is derived from a combination of all the individual correlation speeds.The FFT technology is adopt in the experiment to analyzing the frequency characteristic of the signal. The main vibration frequency of electrostatic signal is found to be in nonlinear relationships with the vibration condition. And it has been found that the fluctuation part of electrostatic signal wave is mainly affected by the mechanical vibration. The electrostatic signal is analyzed at different speed value, and the extraction vibration relevant information can be used for vibration detection.The strip electrostatic sensor is designed for the purpose of theoretical analysis and experimental research. A circuitry based on dsPIC is developed for conditioning the weak electrostatic signal. Experiments show that the electrostatic signal can reflect the characteristics of the system performance. Under all experimental conditions, the relative errors of speed measurement are within ±1.25%and the corresponding curve of the main vibration frequency, amplitude and speed corresponding is obtained.