Research On Eddy-current Embedded Time Gate Angle Displacement Sensor Based On Worm Gear

Displacement measurement is a key factor in achieving closed-loop detection and precise positioning.Embedded displacement measurement is a method based on the principle of time grating sensors,using existing transmission components such as gears and worm gears inside mechanical equipment as sensor rotors,designing sensor stator units,and implementing displacement measurement.Embedded measurement can achieve closed-loop displacement measurement under extreme conditions such as large,heavy,hollow,narrow,etc.At present,embedded time grating sensors often use gears made of magnetic conductive materials as the research object,and use the principle of equivalent magnetic circuit to derive a theoretical model of the sensor for displacement measurement.In fact,machine tools mainly rely on worm gear and worm drive,which is made of eddy current material copper.The principle of equivalent magnetic circuit is no longer applicable.Therefore,using the worm gear as the tested object to design an embedded time grid sensor stator unit to achieve precise positioning is very meaningful,and the existing design theory is still relatively lacking.Based on the above existing problems,this paper proposes a worm gear based embedded time-grating angular displacement sensor based on eddy current flow pattern.The main research project of this topic includes the following aspects: 1)Using the basic principle of eddy current,a theoretical model of embedded time-grating displacement sensor based on copper worm gear is established by solving the impedance method.The theoretical analysis of "straight tooth" and "oblique tooth" sensor elements is emphasized.Finally,the induced electromotive force equation is established to solve the displacement information.The theoretical analysis results show that there is a direct correlation between the sensor error and the stator coil width,especially the fourth harmonic error.2)Taking a worm gear with a module of 3 and a tooth number of 105 as the tested object,a sensor comparison experiment was conducted from both numerical simulation and electromagnetic simulation.The simulation results further verified that the coil width directly affects the sensor error.When the coil width of the "straight tooth" sensor is the slot width,the error value is minimal,and the height of the "straight tooth" coil has a small impact on the uniformity of the traveling wave,only affecting the amplitude of the traveling wave signal;"Oblique tooth shape" sensor has the smallest error value when the coil width is equal to the pole distance.When the coil width of "oblique tooth shape" is constant,the inclination angle of the coil has a certain impact on the sensor error,and 45 ° is the optimal angle.3)According to the needs of prototype experiments,the excitation module part of the hardware system with the STM32H750 controller as the core and the supporting programs of the software system are designed;4)The development of a sensor prototype and the establishment of an experimental platform have carried out basic signal testing experiments,resolution experiments,accuracy experiments,error analysis,and error compensation experiments on the eddy current type embedded time-grating sensor composed of "straight tooth" and "oblique tooth" stators.The experimental results show that the resolution of the "straight tooth" and "oblique tooth" sensor prototypes is 0.5 "and 1",respectively,and the intra electrode measurement errors are 0.005 ° and 0.01 °,respectively.After error analysis,the main errors of the sensor come from installation errors and errors caused by poor uniformity of artificially wound coils.To sum up,the worm gear oriented electric vortex flow type embedded time-grating angular displacement sensor designed in this paper improves the embedded time-grating sensor theory for the measured object of the worm gear and realizes embedded measurement.Compared to traditional time-grating sensors,they have the characteristics of compact structure and less environmental requirements,and can be applied to hollow rotary platforms in closed-loop systems and extremely narrow mechanical equipment industries.