Optimization of High Precision Magnetostrictive Linear Displacement Sensor

摘要

The magnetostrictive linear displacement sensor is a sensor for measuring absolute displacements. The sensor makes use of the magnetostrictive effect and inverse effect to complete the excitation and reception of ultrasonic guided waves, and from the computed time-of-flight of the guided wave the position of the cursor is determined. To improve the measurement accuracy of the sensor, this paper optimizes the system structure and the signal processing method. Improvement made to the bias magnetic field gave the best transduction efficiency; copper rings were used for accurate control of the dynamic magnetic field range, which enhanced the signal amplitude and effectively reduced the hysteresis impact; two-segment receiving coils were used to improve the SNR; and zero-phase filters were used to remove echo signal noise and phase shift. The delay time difference of the echo signal was determined by the cross-correlation algorithm, which determined accurately the value of displacement. The experimental results put the maximum error of the sensor at +/- 25 mu m.