The Research Based On A Seam Tracking Sensor Consist Of Swing Type Adjacent Capacitance Used On Overlap Sheet

Benefit from the rapid development of sensor technology, today, a variety of sensors can be found in industrial control and measur ement fields. Among them, the capacitive sensor has been extensively used in industrial production and manufacturing due to its high s ensitivity, high dynamic frequency response and simple structural principle, etc. Much research of capacitive sensor has been foucsed on the detection and measurement of the measured object in the plane position. However, studies on the achievement of seam tracking through detecting the deviation of welding torch by using adjacent capacitive sensors are still rare. Besides, in the area of welding, the automatic tracking technology of sheet lap welding seam is always a difficult problem. Therefore, this research is aim to provide a new reference for the seam tracking technology of sheet lap welding.Above all, the theory of adjacent capacitive sensor was analyzed. The automatic tracking technology for sheet lap welding seam based on this type of sensor was proposed as well. Meanwhile, a method that using the angle swing of the adjacent capacitive sensor to collect the information of weld seam was also presented in this paper with its mechanism analyzed in detail. On the other hand, the feasibility and advantages of this technique were elaborated theoretically. Furthermore, a mathematical model of the distance between the output capacitance of the adjacent capacitance sensor and the measured workpiece is established.Secondly, another two mathematical models wer e established for the swing scanning of the adjacent capacitive sensors to the sheet lap welding seam, as a result, the optimal swing model was obtained by comparison. In addition, those two models were simulated and analyzed by using MATLAB simulation software. The results showed that the automatic tracking on sheet lap weld by using swing type capacitive sensor is feasible.Next, a method of measuring capacitance value by using AD7150 capacitance-to-digital converter was proposed to solve the problems which existed in the detection of micro capacitance. Moreover, a signal collecting and processing system based on chip ds PIC30f3012 and MCU AD7150 was projected. At the same time, the software system and the hardware circuit of the system were carefully designed. And the stability of such system was verified by experiments. Finally, influences of output capacitance on welding behavior were tested in this paper, and the results were compared with the emulation outcomes of the model after wavelet filtered in MATLAB. The varying patterns of experimental results were agreed with that in simulated one, which further proved the feasibility of the automatic tracking technology of swing type capacitive sensor used in sheet lap weld.