Electromagnetic Analysis And Structural Optimization Of Time Grating Displacement Sensor

Time grating, which makes displacement measurement by use of time measurement,is a kind of grating-sensors, here specially referring to time grating based onelectromagnetic field, mainly including Field-type time grating and time grating withVariable Coupling-Coefficient, they both transform spatial displacement into electronicsignal via electromagnetic field.With the development of time grating toward high-speed measurement andhigh-precision measurement, current structural design and parameters of time grating cannot meet the requirement of improving time grating, and unfortunately, it is hard fortraditional designing method to improve time grating. On one hand, traditional designingprocess not only needs a lot of human resource and investment, but also takes long time tofinish a new design, plus higher and higher consuming level, researching cost of timegrating therefore is becoming heavier and heavier; on the other hand, traditional designingmethod can analyze time grating’s electromagnetic field quite precisely, as a result, timegrating’s output signal has much difference from ideal one, though time grating is able tosatisfy measuring need in most conditions at present. However, in some conditions, forexample, when one wants high-speed measurement, meaning dynamic measurement, timegrating’s output signal will get bad, leading to decline of measuring precision. Consideringproblems appear in the development of time grating and that traditional designing methodcan’t solve them well, a better designing method to improve time grating is in great need.To meet the requirement of time grating’s development, we have done much morework on the analysis of time grating’s electromagnetic field. Besides the analysis of timegrating’s magnetic circuit, FEA(Finite Element Analysis) has been introduced into theprocess of designing time grating. FEA allows us to calculate time grating’selectromagnetic field accurately, not only making simple “quality” analysis but alsomaking “quantity” analysis. What’s more, by way of the analyzing result of time grating’selectromagnetic field, we can find proper access to improve time grating’s structure andthus time grating’s output signal is better enough to be applied in high-speed measurementand high-precision measurement. Another advantage of more work on the analysis of timegrating is from the software–Ansoft Maxwell, which is in charge of most calculation ofelectromagnetic field, because Ansoft Maxwell can help save a lot of time when making anew design of time grating. Ansoft Maxwell allows us to draw models of time grating and then do simulation of those models. Simulating results tell us whether the new design issatisfying or not, and if not, we can modify the models easily by rewriting the parametersof them until simulating results indicate that the new design is good enough.After enhancing the analysis of time grating’s electromagnetic field, some problemsexisting in current time grating are being exposed, some of which can be solved byimproving time grating’s structure. A series of simulating experiments show that timegrating’s output signal is much better and hence, so is time grating’s performance.