Research On Absolute Time-grating Angular Displacement Sensor Based On Magnetoresistance Compound Modulation

Displacement sensor is an important component in many high-end equipment.It has important application value in scientific research and industrial production.The signal of magnetic induction time grid displacement sensor mainly adopts a kind of information demodulation mode of "phase discrimination",which requires higher quality of traveling wave signal.At present,this type of sensor has the following problems: First,there is a parasitic capacitance between the induction coil and the excitation signal coil,the signal is easy to be disturbed;Second,the polar pair error usually contains four error components.Thirdly,the absolute magnetic time-gating sensor has complex structure and large volume.Based on the above reasons,this paper proposes an absolute time-grating angular displacement sensor based on magnetoresistance composite modulation,and carries out the following research work around it.First,based on the basic measurement principle of the time-grating sensor,the paper studies the principle of the magnetoresistor modulation of the magnetic induction displacement sensor and the working principle of the differential circuit of the bridge in the sensor self-induction amplification.Secondly,this paper proposes and designs a rotor multipole scheme with sinusoidal tooth surface for the precision structure of the sensor,which improves and optimizes the sensor accuracy.And the structure of sensor roughing machine is realized by using the unipolar scheme of variable air gap.Thirdly,this paper proposes and designs an absolute measurement scheme based on the differential amplifier circuit of the bridge.The absolute scheme is realized in the form of the combination of the coarse machine and the fine machine.The coarse machine and the fine machine are designed into the same sensing unit to realize the compound modulation of reluctance.The absolute measurement of the sensor is realized by changing the sequence of winding series to realize the switch between the fine machine and the coarse machine.Fourthly,this paper uses the electromagnetic field simulation software to carry out simulation verification and error analysis on the proposed sensor model,and verifies the feasibility of the scheme.Further optimization is made on the designed model to improve the sensor accuracy.Fifthly,the prototype of the sensor is designed and trial-produced,and the principle verification test,resolution test and precision test are carried out.The experimental results show that the absolute time grating angular displacement sensor based on reluctance modulation is proposed in this paper.The resolution is 2.5 " and the error is ±0.01° within the sampling range of 0°?360°,and through error analysis,it effectively eliminates the harmonic components of the fourth order,the experimental results are in good agreement with the simulation results and the theoretical model.To sum up,this topic is based on the electromagnetic induction time-grating sensing mechanism,carried out the research on the principle of reluctance modulation and timegrating sensing principle,and designed a time-grating angular displacement sensor based on reluctance compound modulation.Compared with the traditional absolute grid design which requires two sets of sensor units,this design only needs one set of sensor unit to realize the absolute measurement.Combined with the principle of bridge measurement and coil self-induction,single-phase excitation is adopted to avoid the problem of parasitic capacitance.The rotor adopts sinusoidal tooth surface design to improve the measurement accuracy effectively.