Research On Absolute Angular Displacement Measurement Method Based On Multi-electric Field Coupling

Absolute angular displacement measurement and related sensors are important components in the development of industrial automation and intelligence.Angular displacement encoder not only satisfies absolute positioning,but also realizes high precision measurement,which greatly increases its requirment.As far as grating encoder is concerned,the measurement accuracy depends on the number of its tracks.In order to obtain higher measurement accuracy,the number of tracks must be increased,which will increase the size and weight of the encoder and limit the improvement of measurement accuracy.The structure of absolute grating encoder is much more complex than incremental grating encoder,so relative to incremental grating encoder,absolute grating encoder can achieve relatively low measurement accuracy.The electric field time grating angular displacement sensor based on the principle of "space-time conversion" proposed by the author's laboratory applies four excitation signals(+ sin,+ cos,-sin,-cos)to the sensor electrodes uniformly distributed throughout the week,generates alternating electric field to construct a uniform reference system,and realizes the conversion from space to time reference.Aiming at the problem that the traditional angle encoder can not achieve absolute positioning and high precision measurement at the same time,a new type of absolute high precision time grating angular displacement sensor with multi-electric field coupling is proposed in this paper.It directly generates uniform electric field by using electrical signals,which will not cause energy loss and ensure the stability of uniform reference coordinate system.The absolute positioning is realized by using two-circle structure and one cycle difference between inner N-1 and outer N-pair,which eliminates the cumulative error of incremental structure.A single-loop sensor structure is adopted.Four-channel + sin,+cos,-sin,-cos excitation signals are directly coupled to output traveling-wave signals to achieve high-precision angular displacement measurement.The main research contents of this paper include:(1)The measurement principle of electric field type time grating angular displacement sensor is introduced,and the error analysis of single row sensor structure is carried out,and the error sources and measurement mechanism are studied.(2)According to the basic measuring principle of electric field type time grating angular displacement sensor,a new type absolute angular displacement sensor is designed,and the absolute positioning formula and the absolute positioning error limit are deduced.(3)Using ANSOFT MAXWELL electromagnetic simulation software to simulate and analyze the electric field of the sensor model,focusing on the electric field distribution between multi-electric fields and the influence of different clearance heights between stator and rotor on the error.(4)Make sensor prototype,build experimental system,and test the accuracy and performance of the sensor.(5)Analyzing the experimental results,optimizing the sensor structure,eliminating the irrationality of its structure design and improving the measurement accuracy.Based on multi-electric field coupling,the time grating angular displacement sensor optimizes the sensor structure through theoretical analysis,electric field model simulation and experimental research,and combines theory with practice.Finally,the absolute positioning is realized in any 0°~360° degree range.At the same time,the whole-cycle measurement accuracy of the sensor after harmonic correction reaches ±1?.