| The research and development and application of high-end industrial robots mark the level of national scientific and technological innovation and high-end manufacturing.Sensors,as the "eyes" of industrial robots,play an indispensable role in the development,and their accuracy directly affects the performance of the whole system.Therefore,the research on sensor optimization and innovation has become a hot research direction.timegrating displacement sensor is a high-precision displacement sensor researched and proposed by the Engineering Center of the Ministry of Education of Mechanical Testing Technology and Equipment of Chongqing University of Technology.After more than 20 years of technology precipitation,the time-grating displacement sensor based on different coupling methods is extended to the research of time-grating displacement sensor based on the core idea of "space-time transformation" theory,which has a significant position in the sensor market.This topic is based on the double-layer orthogonal structure(double-layer orthogonal structure refers to the excitation coil structure of the sensor is double-layer structure and the two sets of excitation winds are orthogonal to each other)incremental time-grating displacement sensor,in-depth to the absolute time-grating displacement sensor research,combined with the sensor structure and absolute measurement principle,designed a signal processing scheme suitable for the dual-code channel absolute displacement sensor,the specific main research content is as follows:According to the principle of electromagnetic induction and space-time conversion,the whole process of the incremental displacement sensor measurement is systematically described,including the generation principle of the time-varying magnetic field,the generation principle of the traveling wave signal and the measurement principle of the position in the pole.The mathematical model of the time-varying magnetic field is established,and the mathematical expressions of the induced electromotive force and the traveling wave signal are derived according to Maxwell’s equations.Based on the incremental type,the measurement principle of the absolute displacement sensor with different combinations is deeply analyzed.The signal processing system of the absolute displacement sensor is determined by the absolute measurement principle.According to the mathematical model of the time-varying magnetic field and the structural characteristics of the sensor,the magnetic field compensation driving scheme is designed.The traveling wave signal preprocessing hardware circuit is designed.According to the measurement principle of absolute displacement sensor,the general solution scheme of absolute position and the driving signal generation scheme are designed.According to the principle of traveling wave signal generation,the influence of asymmetric magnetic field on the measurement error is analyzed in the form of mathematical expression.The measurement error requirement of two code channels in the absolute shift decoding scheme is analyzed.The simulation model of absolute displacement sensor was established and verified by finite element simulation.Simulation analysis shows that the magnetic field compensation driving scheme effectively reduces the relative error of the amplitude of the induced EMF at the complementary position of the rotor,and reduces the measurement error of the sensor.The peak value of the measurement error was reduced by37.4% from 58.43 "to 36.56".The absolute position calculated by the position shift solution was basically consistent with the true value,and the peak value of the measurement error was less than one pitch,which further verified the feasibility of the position shift solution.The experimental platform of absolute time-grating displacement sensor composed of grating as calibration system is built,and the test of signal processing hardware circuit board is completed.A series of experiments were carried out based on the circuit board to analyze the sensor.The experimental results of the magnetic field compensation driving scheme show that the magnetic field compensation driving scheme improves the measurement accuracy of the sensor in the opposite pole,and the measurement error within the pitch is reduced from(-25.5,18.3)"to(-20.8,12.6)".The experiment of absolute time-grating displacement sensor shows that the maximum measurement error in fine machine is not more than ±18.2",and the maximum measurement error in coarse machine is not more than±150.4".The whole measurement error of the sensor was within(-19.8,24.8)",which verified the feasibility of the absolute displacement decoding scheme. |
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