The Research Of Parasitic Time-Grating Displacement Sensor Electrical System And Error Correction Model

Time grating displacement sensor avoided the traditional grating on precision machining,precision reticle requirements,so it is used more and more widely in the field of mechanical processing and other precision displacement measurement.However,the time grating displacement sensor is very difficult to be used in large scale,high speed,heavy load,strong vibration and heavy pollution environment.In order to solve these problems,the research team put forward the parasitic time grating displacement sensor.,to the measured the gear,the worm gear,etc directly.as a uniform indexing "teeth gate",as the traveling wave generating device,then the clock pulse for precision measurement,thus the original mechanical transmission vice into "with detection function of transmission side".But in the measurement process of parasitic gate,there also have the following problems: one is the electrical system of parasitic grating displacement sensor about each module using different chip,the joint is difficult to debug and affect the measurement stability;second is that high accuracy measurement of grating displacement sensor need high precision clock interpolation,and the interpolation clock also does not meet the accuracy requirements.The three is more measurement error components,researching on model error correction,it can reduce the error.According to the problems above technical existence of parasitic time grating displacement sensor in measurement,there designed the electrical system and error correction model.It used a single chip microprocessor to design the integrated treatment of electrical system;the accurate measurement of high precision time to digital converter;the pitch harmonic error model of error correction;realized the measurement of high precision and high stability,in order to improve the efficiency,reduce production,realize industrialization objective.This design focuses on the electrical characteristics of the parasitic time grating displacement sensor,using STM32F4 VGT chip as the main controller chip that integrated the FPU and DSP,high frequency arm cortex-m4 processor,to control AD9958 digital frequency direct synthesis(DDS)technology to achieve the excitation signal,using high resolution TDC-GP2 digital clock converter to the sensor dynamic,measuring head induction signal phase difference high speed time measurement,in STM32F4 VGT chip integrated FPU and DSP instruction set for data processing and algorithm realization,inthe discrete measurement by pitch harmonics correction model error correction can be achieved the design of measurement system.The measurement platform is set to operate the experiment and research.The experimental results show that the 48 pole parasitic time grating sensor for the entire week(0 to 360°)stability achieved ±0.5″ and error reached ±2.3″,the pole(0 to 7.5 degrees)the error reached ±2.5″,meet the requirements of the system,realized the high stability,high precision measurement.