| Time grating displacement sensor is one of the high-precision displacement sensors,which completes the space measurement by measuring the time and then measures the displacement.It is to solve the large,medium,empty,oil contamination,noise,vibrational and other extreme environments as well as the displacement measurement in special conditions.However,the traditional parasitic time grating displacement sensor relys on manual winding way as the sensitive element,which has the disadvantages of low transmission efficiency,poor consistency and interfered man-made factors easily.It has a great effect on the measurement accuracy of parasitic time grating displacement sensor.The magnetic sensitive element is an electromagnetic induction element which can output the electric signal according to the change of the magnetic field,and it has been applied into the field of measurement,for instance: magnetic reading head,magnetic field testing,etc..In addition,compared with the winding coil,the magneto sensor has the advantages of small size,high sensitivity,strong anti-interference ability,low power etc..For this reason,to study the magnetic sensor is served as the sensitive element of parasitic time grating displacement sensor in the paper.The work and achievements presented in this paper are summarized as follows:(1)It is Based on the examining of the input and output properties of the magneto sensor,and bound with the measuring principle of the grating displacement sensor to deduce the measurement principle of parasitic time grating based on magnetic sensor by using the theory.According to the the analysis and comparison of the input and output properties of Hall element,AMR element,GMR element and TMR element,the experiments are done on each magnetic sensor to verify.It theoretically and experimentally,draws the TMR chip based on TMR element is able to meet the requirements of parasitic time grating measurement.(2)The magnetic steel(size,shape,material),the gap between magnetic steel and magnetic sensitive element,the air gap between magnetic sensitive element and the measured object are the main factors that influence the output of the magnetic sensitive element,and using electromagnetic field analysis software(ANSOFT Maxwell)to research the corresponding parameters for them.According to the conclusions of the simulation analysis,and the structure parameters of the sensor can be established.According to theprinciple of electromagnetic field simulation and parasitic time grating measurement,we design the two phase space orthogonal TMR chip arc tool,so as to determine the position of the chip,and then finish the structure design of the sensor.(3)According to the principle and application requirements of parasitic time grating,a chip STM32F407,highly integrated and powerful,is used as its control,what's more,the corresponding hardware circuit and Program software are designed.(4)According to the measurement principle,the experimental platform is built,the higher precision Heidenhain grating is used to carry out the precision calibration experiment.The peak value of the primary error peak is 140?.The error analysis shows that It is mainly composed of mechanical and electrical errors.If the error correction technique is used to correct the error,the peak value of the error is 8?.In summary,this paper proposes a measurement method based on magnetic element instead of wound coil by analyzing the advantages and disadvantages of wound coil as a sensing element,gives the measurement principle of parasitic grating displacement sensor based on magnetic element,designs the sensor structure and develops a sensor prototype.Experimental results show that the magnetic sensitive element as a sensing element can realize high precision displacement measurement.Therefore,this research provides a new research direction for the displacement measurement of parasitic grating displacement sensor under special conditions such as large,medium and empty. |
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