Investigation Of The Output Characteristic For Magnetostrictive Displacement Sensor Under Helical Magnetic Field And Stress

Magnetostrictive displacement sensor is broadly used in automatic control system,super-precision machine processing,intelligent robot control technology etc.due to its advantages of non-contact,high precision,long service life,and high reliability position measurement.However,the measurement of magnetostriction of the waveguide wire and calculation of the sensor output characteristic with existing model still need to be improved,and the study on magnetostrictive displacement sensor under both the helical magnetic field and stress is limited.In order to solve these problems,this paper focuses on modeling the output characteristics of magnetostrictive displacement sensor.Firstly,a new method is proposed that can measure the magnetic property of the waveguide wire.With this method,the influence of vacuum magnetic heat treatment on waveguide wire is analyzed.In addition,the research on the relationship between Wiedemann effect strength and helical magnetic field provides an access to study the influence factors of Wiedemann effect.The Galfenol waveguide wire with diameter of 0.05 m is selected as the sensitive device of magnetostrictive displacement sensor compared with the experimental result.Secondly,the signal generation mechanism of magnetostrictive displacement sensor and the propagation process of torsional wave are analyzed from the angel of magnetic domain.The output characteristics of sensor are calculated after establish the mathematical equation of the output voltage.According to the model simulation and the experimental data,the output voltage of the sensor is proportional to the helical magnetic field intensity when the excitation magnetic field equals the bias magnetic field.In addition,in accordance with the high mechanical performance of Galfenol and conception of effective magnetic field in the Jiles-Atherton model,the effect of stress field is added to the output voltage model of sensor under helical magnetic field,then the output characteristic model of magnetostrictive displacement sensor is built under the helical magnetic field and stress.The result shows that the stress on the sensor should be less than 50 MPa to obtain good output characteristic.At last,the magnetostrictive displacement sensor prototype is designed and manufactured,and the test platform is established.The output characteristics of sensor under both the helical magnetic field and stress are analyzed through experiments.The influences of bias magnetic field,excitation magnetic field and stress on the output characteristics are determined.The experimental results are in line with the output of the model,so the accuracy of the characteristic model of the magnetostrictive displacement sensor meets the requirement.The results indicate that the output voltage is 57.1 mV in the condition of 3.5 kA/m excitation magnetic field and bias magnetic field,and a stress of 5 MPa.What's more,all the static indicators work well with a linearity of 0.035%,repeatability of 0.0045%,and hysteresis of 0.00319%.The measurement method of magnetostrictive materials and the output characteristic model of magnetostrictive displacement sensor proposed in this dissertaton is an initial.It provides a new method for measurement of magnetostrictive materials,study on the Wiedemann effect,and theoretical foundation for the research on the output characteristics of magnetostrictive displacement sensor.