The Design And Realization Of The Speed And Location Detection System Based On The Inductive Looped-cable

Taking the low-speed maglev train test line of Tang Shan as the applicationbackground, this paper accomplishes the design and realization of speed and positiondetection based on the inductive looped-cable. This system has strong resistance tointerference and high reliability, which could detect speed and relative position oflocomotive rapidly and accurately. Furthermore, the cross structure of inductiveloop-cable can effectively inhibit clutter electromagnetic interference. Therefore, speedand position detection system based on crossed inductive looped-cable owns a highlypractical value, and has a good prospect.Firstly, the schematic design is proposed by putting forwards two different signalhandling methods, and their advantages and disadvantages are compared. Due to thedefects of low resolution in the design above, the signal processing methods ofdemodulation, sampling and lookup are put forward in this paper.Then this paper calculates the electromagnetic fields produced by the inductiveloop-cable and analyzes influences of loop width and detecting height on the magneticfield distribution, and the detecting coil which is suitable for the new sensor is designed.For the wave reflection on the long-distance transmission line, this paperestablishes the propagation equation of inductive loop-cable, and analyzes the wavereflection existing in the inductive loop, then impedance matching is taken in theterminal of the loop line to weaken the effect of wave reflection. Finally, the calculationresults are validated by experiments.Finally, the system based on amplitude detection, phase detection and the signalprocessing methods of demodulation, sampling, lookup are completed respectively. Andthe systems which are accomplished have been tested on the low-speed maglev train testline of Tang Shan. And the test results show that the system of speed and positiondetection based on the inductive looped-cable can satisfie the design requirements andhas a good performance.