| When High-Temperature Superconducting(HTS) maglev vehicle is in the course of operation, the distance between the bottom of vehicle and the rail is a essential data. The distance must be detected quickly, because it relates to the safety of trains. HTS maglev vehicle has the extremely high speed, which requires high-speed, high-precision measurement.There is a strong magnetic field around the rail, aimed at this point, a few kinds of distance measuring sensors including ultrasonic sensor, eddy current sensor and photo-electricity sensor are analyzed and compared. At last, the method using single-point laser triangulation based on linear CCD is chosen.The thesis deliberate over the theory of triangulation on distance measurement, and analyzed the parameters of system. The signal extraction methods-two-value processing and DSP method from CCD analog video signal are expatiated on with their merits and shortcoming analyzed as well. In two-value method, system uses center of image, choice of capture edge and judgment pixel width to improve the technical capacity of interference. In the DSP method, system uses the center of gravity-algorithm, which combines average-voltage value and a fixed threshold value, to determine precise location. In the text, the hardware and software of the two methods are expounded detailedly and separately.Finally, a portable measuring instrument prototype is designed and made with DSP TMS320F2812, using two-value processing method. Polynomial curve fitting and piecewise linear approximation are analyzed and compared. System is demarcated with piecewise linear approximation. The measuring instrument measuring accuracy achieves±0. 1mm.and the measuring range is 58mm-139mm,and the measuring frequency is 100Hz,and the instrument can resist the certain intensity of the light disturbance. It has achieved the project request, and met the practical purpose.
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