Research On The Digital Grating Eddy Current Sensor

Grating Eddy Current Sensor (GECS) is a new displacement sensor based on Eddy Current Effect. Through changing the couple area between the planar coil and reflector, it can sense the large straight displacement. Compared with other grating sensitive devices, the GECS features high sensitivities, easy to shield, low output impendence, high output driven current, compactness, low cost and easy to assembly. Because of the Eddy Current Effect, the GECS is water-proof, un-sensitive to the moisture, oil and so on. Currently, GECS has been applied in the digital water-proof caliper. In view of the complicated background of the digital water-proof caliper, this article posed out a kind of digital measurement system based on GECS and the layout of the coil and reflector.This thesis analyzed several kinds of the water-proof caliper. In view of these composition and work principle, we find that its application circuits are based on the analog and digital circuits. So, we provide a special measurement method to make the sensor output as digital flow.Then, it introduces the basic principle of the GECS, and employs the typical circuit principle to explain the exact equation in the eddy current phenomenon, given the equivalent circuit for the planner coil, reflector and the whole system, provide some advice in designing the GECS. Using FEA to simulate and analyze the input-output curve of the GECS.This article designed several kinds of sensor with different wave length, high sensitive measurement circuits and phase module based on the structure of the sensor layout, then change the variation of displacement into the variation of the signal. Finally, it accomplished the digital output throughout of the digital phase locked technology.Output characteristic experiments are taken on three GRATINGs of GECS whose geometrical parameters are different. We discuss the input-output curve and the sensitivities of the GECS. This research provides the improving orientation in order to enhance the precision of GECS.