Absolute Linear Time Grating Displacement Sensor Based On Planar Magnetic Induction Coil

At present,with the rapid development of intelligent manufacturing,the sensor,as a key component of the full closed-loop control of linear motors and CNC machine tools,has more and more stringent requirements for its high precision and precise positioning.The machining accuracy in the full-closed loop system depends on the accurate feedback signal of the absolute position sensor to its position.The accuracy of the feedback signal is the key to realize the high precision and high efficiency of CNC machine tools.The absolute position sensor widely used in industrial processing is absolute grating,but absolute grating products basically rely on imports.It is difficult for my country to make breakthroughs in absolute grating technology.The technical difficulty in the development of absolute grating sensors lies in the complex absolute coding and almost harsh The processing technology.Absolute gratings must also consider the signal stability and the complexity of the lithography process of the encoding while encoding and decoding.As the size of the sensor decreases,the manufacturing difficulty required for complex and high-precision scribe lines also increases geometrically.The grating needs to be scribed through multiple processes.Only a nearly harsh processing technology can ensure that the scribed has a regular shape,Evenly arranged dense grid lines,these are also difficult to achieve in my country's current processing technology.Therefore,in view of the current situation that grating technology is difficult to break through,this paper proposes an absolute linear time grating displacement measurement sensor based on planar magnetic induction to meet the requirements of machine tool processing position feedback.The main research contents of this paper are as follows:(1)Planar magnetic induction time grating absolute displacement measurement modelOn the basis of the incremental linear time grating displacement sensor structure,this paper proposes a new absolute measurement method of "coarse channel positioning + fine channel measurement".The study adopts two rows of different pole-pitch "?" shape fixed-length structure windings and moving-scale sinusoidal induction windings to construct two rows of spatial displacement signals through electromagnetic induction,and establish a linear mapping relationship between the phase difference of the two rows of spatial displacement signals and the movement distance.Modeling and analysis of the sensor's error law are carried out by deriving the mathematical theory of the sensor.(2)Electromagnetic simulation and sensor parameter optimizationThe sensor measurement model is simulated by Ansys Maxwell software to verify the correctness of the measurement method.According to its structural characteristics,the two sensing units of the sensor are combined and analyzed,and the most suitable winding distance is selected to change the error size and harmonic components.Through the spatial phase shift of the induction winding to suppress the harmonic components of the measurement error,an optimized sensor measurement model is established and simulated,verified and analyzed.(3)Sensor detection system design and experimental researchAn absolute sensor experimental platform was built,the simulation model was made into a physical prototype using PCB printing technology,and the signal processing circuit and data acquisition module were designed to build the sensor system.Through experimental research,the signal and accuracy of the absolute sensor prototype before and after optimization were tested.The error correction experiment was carried out on the optimized prototype using the harmonic correction method.The results show that the sensor has a measurement accuracy of ±10?m within the measurement range of 0?120mm after correction.It has low cost,strong antiinterference ability and good stability and other advantages.