| The control and measurement for the cable eccentricity is important for the cable production. The cable eccentricity not only causes the huge waste of the material, but also affects the performance parameters of the cable. The eccentricity measurement system was studied in this paper in order to realize the online measurement.By widely reading plenty of literatures, the present condition and the developing trend about the cable eccentricity testing overseas are achieved. Based on that, measurement principle of the eddy current sensor is given in detail, and the project and design of the eddy current measurement system for the cable eccentricity is brought forward.The content of the paper is mainly composed of three parts: the design of sensor, the inferior subsystem and the superior subsystem. In the second chapter, equivalent circuit of the eddy current sensor is firstly analyzed. Based on that, the carrier signal generating circuit that is realized by the LC periodic circuit is introduced, thus, the carrier signal of standard frequency is obtained through the trimming capacity. Subsequently, the disc type rotational armature generator and the rotational coupling transformer are separately leaded in to realize the power supplies of the carrier signal generating circuit and output of the measuring signal. Finally, the realizability of this measuring method is proved by a set of testing curve.The amplitude discrimination circuit, the filter circuit and the amplifying circuit are designed to transform AC analog signal that the eddy current sensor output to DC analog signal, thus, the DC analog signal can be received by AD converter. To meet the requirements of measuring accuracy, 12 bits AD converter TLC2543 is applied in the inferior subsystem, and the transforming error is reduced to 1/1095. Digitalized measuring signal is processed in the AT89C52 single chip that is the core chip of the inferior subsystem, and the measuring result is obtained, then it is transmitted to the superior subsystem through the serial-parallel interface of single chip. The hardware structure and program of the superior subsystem are disserted in the last chapter of the paper in detail. The keyboard with 16 keys and the lattice LCD controller are controlled by the PIC16C73 single chip that is the core chip of the superior subsystem, and the corresponding hardware circuit and flow chart of the program are given in this chapter. On programming the monitor software, we take full advantage of the characteristic which there are two display modes, text and graph display mode, in the FM240128A lattice LCD controller, then the accurate display of measuring result is obtained. |
