Research On Absolute Single-mute Time Grating Displacement Sensor Based On Time-varying Magnetic Field

With the continuous development of industrial automation,sensing technology as one of the three modern information technology has been deeply into all kinds of production and manufacturing sites.As one of the core functional components of closed-loop servo control system,the development process of displacement sensor with the purpose of acquiring position information also affects the development of automatic control field and even highend equipment manufacturing industry.The increasingly severe market competition also puts forward higher requirements to the displacement sensor.Absolute measurement is the first choice in the high-end market because of its advantages in efficiency and reliability,and it is the main research direction of future displacement sensors.But at present,displacement sensor is still focused on the incremental measurement research,a few of the absolute measurement research is also based on multi-channel measurement.The multichannel absolute measurement scheme is simple in structure and easy to implement,but the problems such as inter-channel interference and installation complexity have not been solved well,which restrict its application in some occasions.The single channel absolute measurement avoids the channel interference and the structure is more perfect,so it is possible to improve the comprehensive performance of the sensor.Based on this,this paper proposes a measurement structure scheme of single-channel absolute time-grid displacement sensor,and carries out the following research work:(1)Based on the incremental grating displacement sensor sensing principle of induction signal phase and child magnetizer linear relationship between the rotation angle,put forward using non-uniform dynamic sub magnetizer induced behavior,the traveling wave magnetic field which results in different dynamic sub magnetizer to generate the corresponding phase advance or delay,decorate absolutely induction coil and incremental induction coil single of anode and pick up the whole week,respectively,the magnetic field,The phase difference between the two was used to realize the polar marker.The absolute measurement scheme of single code channel was designed and the mathematical and physical models of the sensor were established;(2)According to the established mathematical model and physical model of the sensor,numerical simulation and transient electromagnetic field finite element simulation were carried out by MATLAB and ANSYS software respectively.The theoretical feasibility of the sensor was verified by the phase analysis of the numerical simulation signal,and the analysis of the finite element simulation signal showed that there was irregular signal interference in the phase difference coding curve.Based on the analysis of the magnetic field constraint and the structure of the excitation magnetic field,the magnetic leakage phenomenon and the uneven distribution of the excitation magnetic field are determined at the edge of the actuator magnetic guide;(3)In view of the magnetic leakage phenomenon at the edge of the actuator magnetic guide tooth slot,a split structure was proposed to enhance the constraint of the magnetic guide tooth and accelerate the attenuation of the slot.The verification of this model shows that the amplitude of all inductive signals was improved.Aiming at the problem of uneven distribution of excitation magnetic field,the method of excitation coil amplitude and conductor arrangement was established to improve the uniformity of excitation magnetic field and excitation intensity.According to the analysis of the whole cycle finite element simulation results of the optimized model,the regularity of phase difference curve was significantly improved.Combined with the error law,the signal filtering method was determined to determine the feasibility of the sensor structure scheme;(4)According to the simulation and optimization of the sensor model structure,the sensor prototype parts and assembly methods were designed,and the prototype experimental platform was built,the signal testing and data acquisition work was carried out,the sensor error signal components were analyzed,and the signal error source was derived,on this basis,the sensor error compensation method was studied;The experimental results show that the single-channel absolute time-gate displacement sensor structure with 18 poles and 0.5° offset angle is adopted.The original measurement error is ±185.77'',and the phase coding curve has monotonic characteristics throughout the whole cycle,which can be used to determine the corresponding polar.The experimental results show that the method can realize the absolute displacement measurement without increasing the sensor size and the number of code channels.