Research On Miniaturized High Precision Absolute Angular Displacement Time Grating Sensor

As the mainstream of the development of displacement measurement,precision displacement measurement technology is widely used in the fields of high-end CNC machine tools,intelligent manufacturing equipment,and national defense weapons and equipment.With the advancement of technology,the requirements for angular displacement encoders are getting higher and higher.It is necessary to meet not only high-precision measurement,but also absolute position measurement,and miniaturization of encoders.At present,the most widely used encoders on the market are absolute encoders.Due to the high market share of encoders and the complexity of encoding technology and manufacturing processes,encoders have always represented the cutting-edge field of high-precision absolute encoders.Capable of R&D and manufacturing,most of the encoders used in China are imported from developed countries.The developed foreign countries that have mastered the precision measurement technology of gratings have imposed technical blockade on China's high-precision angular displacement grating products,and implemented price monopoly on low-end and mid-range products,which have seriously affected China's economic development and national defense security.Therefore,the development of miniaturized high-precision absolute angular displacement sensors appears necessary and urgent.The research team of the author changed his mind and proposed an electric field-type circular time grating sensor based on the "space-time conversion principle".The alternating electric field was used as the reference frame of uniform motion to convert the spatial displacement measurement to the time difference measurement.Based on the previous research of electric field type angular displacement time grating sensor,this paper carried out a new type of miniaturized high precision absolute round time grating sensor.The main research contents are as follows:1)Introduced the measurement principle of electric field type time grating sensor,briefly analyzed the development of electric field type round time grating sensor from double-circle structure to single-turn structure,and proposed a kind of the miniaturized high-precision absolute time grating sensor uses a differential structure to achieve the absolute positioning of the sensor;Meanwhile,it adopts a time-multiplexing structure,which can eliminate the crosstalk between the two circles of excitation electrodes,ensure the measurement accuracy,and reduce the circle of sensing electrodes,facilitate the miniaturization of the sensor;Finally,the multi-sensor cascade method is adopted to improve the resolution of the sensor,and the sensor is changed from a double-sided outlet to a single-sided outlet,which is convenient for the application of the sensor.2)Based on the measurement principle of the electric field type time grating sensor,a measurement error model of the sensor is established,and the effects of the three parameters of the signal amplitude,phase,and the presence of harmonic components on the error in the pole are analyzed in detail,and the law of error variation is revealed.The influence of eccentricity and non-parallel installation of the moving stator on the measurement error of the whole cycle is analyzed,which provides theoretical guidance for the installation and application of the sensor.3)An experimental system is designed and an experimental platform is set up.A prototype of a sensor with an outer diameter of ?=57 mm and an inner diameter of ?=35 mm was manufactured by using the PCB process,and the performance of the sensor was tested.After the test,the experimental data was analyzed to find out the reasons affecting the experimental accuracy,and the sensor structure was optimized to further improve the sensor measurement accuracy.In summary,the final experimental results of the miniaturized high-precision absolute round-grating sensor developed in this paper show that the original measurement accuracy of the sensor in the range of 0°?360° has reached± 25",and it can achieve absolute position positioning.The same size has reached the international advanced level.