| As a feedback component of position closed-loop servo system,the position detection performance of displacement sensor determines the precision of servo system to a large extent.Therefore,the research on the related technology of displacement detection is one of the important basic researches in the process of industrial upgrading at present.A high level of displacement detection capability will also inevitably strengthen the competitiveness of our high-end manufacturing industry.As an important part of displacement measurement,planar two-dimensional displacement detection is required in a large number of industrial applications and basic scientific research.At present,two one-dimensional displacement sensors are often used for two-dimensional measurement.Although this method solves most measurement scenarios,it has some limitations.First,the measurement cost is high,including the sensor cost and installation and maintenance cost;Secondly,the combination measurement has measurement and installation error,which is not conducive to high precision measurement.Third,more installation space is needed,which goes against the development trend of miniaturization of equipment.In order to solve the above problems,this paper uses the time-grating measurement technology to carry out the research of planar two-dimensional sensor electrical system based on multi-frequency magnetic field coupling,and is committed to solving the integrated and miniaturized two-dimensional displacement measurement.This paper mainly studies the following contents:(1)Research on modulation and demodulation methods of two-dimensional displacement information of sensors.Based on the one-dimensional time-grating displacement modulation method,a coupling method of 10 k Hz traveling wave field and 200 k Hz standing wave field was proposed to complete the traveling wave and standing wave modulation of displacement information in two measured directions respectively.In view of the two displacement modulation methods,three displacement information demodulation schemes are proposed respectively.After comparing the advantages and disadvantages of each scheme,the X direction is determined to adopt the high frequency clock interpolation scheme,and the Y direction is adopted the switch amplitude detector scheme.(2)Research on error analysis and Compensation Method of sensor electrical system.From the point of view of analyzing the transmission loop of the sensor signal chain,the weak link affecting the measurement accuracy is found,and the optimization direction is proposed for the electrical system.For X direction,the electrical compensation method of sensor process and installation error and hardware average method of reducing random error without affecting dynamic performance are proposed.For Y direction,the parameter asymmetry error of filter circuit is eliminated by using time-division multiplexing method.(3)Sensor electrical system design.The electrical system of sensor is divided into two parts: excitation signal generation and induction signal processing.The electrical system design is carried out to strengthen the weak link of the transmission loop of the sensor signal chain.For excitation signal generation,a current type drive circuit based on feedback control is designed in X direction,which lays a hardware foundation for electrical system compensation of process and installation errors.High-order filter is designed in Y direction to eliminate the effect of high-order harmonics.For induction signal processing,filters in both X and Y directions are designed to eliminate magnetic field coupling and suppress interference,which improves signal-to-noise ratio.X direction design multi-voltage comparison circuit to realize hardware averaging;Y direction through the analog switch to complete the filter circuit time-sharing multiplexing.(4)Build an experimental platform to measure the performance of sensors and electrical systems.Design and debug the electrical system,complete the experimental platform;The experimental results show that the original in-polar error is ±32 μm in the X direction and±27.5 μm in the Y direction,and the coupling error in both directions is less than 1μm.The electrical error compensation experiment in X direction is carried out to verify the correctness of the error theory,and the error in X direction is reduced to ± 16.5 μm. |
