| The development of high-end manufacturing industry cannot be separated from precision displacement sensor.Reluctance displacement sensor has the advantages of strong anti-interference ability,high precision and good stability,and is widely used in industrial manufacturing.Absolute measurement has strong reliability and can improve production efficiency,which is the main research direction of displacement sensor in the future.At present,the absolute measurement generally adopts the differential multi-channel structure and the differential common signal source structure.Although the structure is simple and reliable,the signal coupling and the large size of the sensor in the differential structure will affect the accuracy of the sensor.The single-code channel absolute sensor structure with biased moving magnet can reduce the volume of the sensor and reduce the interference to a certain extent,but the high machining requirements for the tooth rotor and the serious magnetic leakage result in the low accuracy of the sensor.In view of this,this paper proposes a research scheme of magnetoresistive absolute time-grid displacement sensor based on ring plane aperiodic structure by using copper foil rotor to constrain the magnetic field on the basis of planar circular time-grid,and carries out the following research work:(1)In order to solve the problems of complex installation and signal coupling of existing differential absolute displacement sensors,an aperiodized copper foil rotor was proposed to constrain the magnetic field,and the relationship between three output induced signals was constructed to determine the opposite pole.Absolute measurement was realized by combining the output induced signals of the whole cycle.Perfect the realization scheme of absolute measurement and establish the theoretical model of sensor.(2)Simulation analysis is used to verify the theoretical model of the sensor.Matlab software is used to simulate the theoretical model and verify the feasibility of the model.Taking the integrated tooth rotor sensor model as the control group,Ansys finite element simulation analysis of the integrated tooth rotor sensor model and array copper foil rotor sensor model was carried out respectively.From the original signal processing,the phase difference coding curve has monotonicity in the whole cycle,but the regularity is weak,so it can not be used for polar judgment.By analyzing the magnetic dense cloud map,it is determined that the distribution of magnetic leakage and magnetic field is uneven at the edge of the copper covered area and the non-copper covered area.(3)To solve the problem of magnetic leakage phenomenon and uneven distribution of magnetic field,the model was optimized by cutting rotor matrix.By analyzing the simulation results,the waveform of the three induction signals is more regular and the amplitude of the induction signals is improved.The regularity of the phase difference coding curve is enhanced and the filtering method is combined to determine the sensor structure scheme.(4)The optimized sensor model is developed,the experimental platform is built and the communication between the upper and lower machines is realized,the prototype signal and the stability of the system are tested,and the error of the experiment is ensured within the accuracy range.The data is collected,the error is processed and analyzed,and the error correction method of the sensor is studied on this basis.The experimental results show that the original accuracy of the whole cycle measurement is 165.01 by using the absolute sensor structure with 18 poles and 0.5 °deflection Angle.After the measurement results were corrected by Fourier series correction method,the average accuracy of 6 measurements of the prototype was 12.14.The experimental results show that the scheme of copper foil rotor with aperiodic structure can realize the absolute displacement measurement in the whole cycle. |
