Turntable bearings are widely used in the fields of national defense, industrial manufacturing and precision machining, and the precise measurement of their displacement is very important. A cylindrical embedded magnetic field angular displacement sensor based on PCB process is presented in this paper. In this design, the coil required by the electromagnetic induction sensor is distributed in the flexible PCB , and there is no need to provide a specific shape of the iron core to place the metal coil, which is easy to achieve embedded measurement. In this paper, the magnetic field distribution of cylindrical coil is modeled according to Biot-savar's law, and the mathematical relationship between magnetic induction intensity and coil structure is obtained. The coil structure is designed according to the mathematical relationship obtained. The feasibility and accuracy of the theoretical model were verified by finite element simulation software. Finally, a prototype was made for measuring angular displacement of bearing with inspection. Experiments show that the resolution of the sensor can reach 0.5 "and the original error is ±80" in the range of 0~360°.
In fields such as wind power, shipping and so on, there are great demands for linear and (or) rotary precision positioning of heavy or supersized mechanicals; and the areas where required high reliability, like aerospace and weaponry, there are also urgent needs to perform synchronous position measurement through a multipoint redundant structure in a narrow space to deal with the impact of strong shock vibration and electromagnetic interference. As grating encoders and magnetic grating encoders are difficult to meet the requirements of the extreme space size and working environment above, this paper proposes an embedded measurement method that integrates magnetic sensing modules (MSMs) and the measured transmission part. Its principle is that place several small MSMs next to the measured transmission part to form a specific time-varying magnetic field, and then make use of the periodic equipartition structure of the transmission part itself to realize the permeance modulation to get the induced voltage that reflects the position change, finally, calculate the displacement. Based on the magnetic equivalent circuit (MEC), this paper builds an embedded time-grating (ETG) sensor model applied to gear parts. According to that, take a spur gear as the object for rapid optimization design, which is verified by three-dimensional (3-D) time stepping finite element analysis (TSFEA). Finally, an experimental prototype is made by the optimized sensor parameters, and experimentally verify the results. The results show that the high-accuracy measurement is realized, and the measurement error achieves ±5″ within the entire range.