Design And Realization Of Magnetostrictive Displacement Sensor Based On CPLD And SCM

With the development of science and technology，higher requirements for the displacementmeasurement are raised. Magnetostrictive displacement sensor is a kind of displacement sensor inwhich magnetostrictive effect is used to transform the displacement measurement to timemeasurement. It has incomparable advantage over other instruments in high precision displacementmeasurement. The performance and cost of the domestic and overseas magnetostrictive displacementsensors were analyzed and a kind of high-precision and low-cost sensor was designed in this paper.The principle of the magnetostrictive displacement sensor was analyzed. The finite elementanalys is for bias magnetic field and invigorative magnetic field, and the mathematics model of thesensor output was done. The mechanical structure of sensor in material of waveguide wire, torsionwave acquisition device and bias magnetic field was optimized.To improve the measurement accuracy of the sensor, the sensor based on CPLD and single chipmicrocomputer was present in this paper. Hardware and software have been designed. Hardwarecircuit include power supply circuit, pulse amplification circuit, echo receiving circuit, high precisiontime measurement circuit, serial communication interface circuit, and a variety of custom outputdisplay interface circuit.Software part mainly include the data transfer procedures, the digital filterprogram, display program, the output voltage program, Modbus communication program. After thesystem debugging, calibration experiment platform was set up and the static performance of sensorwas analysed. The experimental results show that the sensor performance meets the design targets.Compared with the traditional measurement system, this system has the induction pulse digitalcircuit and the hardware and software filtering algorithm. It effectively eliminate the secondary echointerference, take full advantage of the single chip microcomputer, such as good data processing,man-machine dialogue and make most of CPLD’s surperiority, such as fast and accurate timemeasurement, convenient and flexiable programming and etc. This system simplifies the circuitstructure, improves the time measurement accuracy, cuts down the cost, and facilitates the sensorminiaturization and engineering application.