The Mechanism Of Angular Displacement Sensing With Magnetostrictive Guided Waves And Experiments

Currently, there are many sensors for angle measurement.The method they use are different and the performance is also very different. At the same time, new methods of angle measurement based on new principles are invented one after another.The magnetostrictive displacement sensor(MDS) is widely used in the measurement field because of its high precision,high reliability and security, free maintenance and self revision.This paper firstly introduces the operational principle of magnetostrictive displacement sensor and then proposes a new method of angular displacement measurement based on the magnetostrictive theory. In the mechanism, the paper firstly analyzes the magnetic field of the cylindrical magnet and compares the signals when the magnet is vertical and parallel to the waveguide wire. The stress-strain relationship of the circular waveguide wire is then analyzed and the influence of elastic deformation and plastic deformation on torsional wave signals is studied by experiment.The paper then tells how to manufacture the circular waveguide wire to get the best signal.After that,we conduct the design of magnetostrictive angular displacement sensor from two following aspects: mechanical structure and circuit. In terms of the mechanical structure,the reason for the blind area is analyzed,then two solutions to eliminate it are proposed and their performances are compared.As the main parts of the sensor,the structure of a disk is designed to fix the waveguide wire.The variation of the signal with the lift-off of the magnet is studied by experiment.A mechanism which can rotate surround the circular waveguide wire is designed.After that,the overall structure of the sensor is given.The hardware design includes power supply design,the excitation pulse generating circuit design, signal amplification and filter circuit.At last,the sensor is assembled and the performance is tested.The result of the test indicates that the magnetostrictive angular displacement sensor has high accuracy and stability,and high value.