Electroes Structure Modeling Analysis And Detection Technology Research Of Rotational Gyroscop

With the development of inertia device, study on gyroscope has been launched around the world. In order to solve the problems of the existing rotational gyroscope and improve the accuracy, the MEMS center of HIT presented a new structure kind of Balldisc rotor-based gyroscope. In gyro system, the capacitance detection section determines the performance of the device directly. So in this thesis a research on the detecting capacitor electrode was started, aiming for improving the linearity and sensitivity of the detection result in the differential capacitance detection.In the thesis the applicable conditions where the position changes of rotor can be described by the capacitance change and the error that existed were discussed. The detecting capacitance was used mathematical modeling to calculate when there was an input angular velocity. Then the Maxwell 3D was used to model and simulate the differential capacitance structure and the factors affecting the differential capacitance detection results were discussed. The edge effects of capacitors were analyzed and solved by adding protection electrode plate to improve the accuracy of detection. Then the detection scheme of the ball-disc rotor-based gyroscope was introduced, the detection circuit included a charge amplifier, a differential amplifier, phase sensitive demodulation and low-pass filter sections. The transfer functions of each part of the circuit were derived. With capacitance values obtained by finite element simulation, the process of output voltage changing where there was an input angular velocity was simulated. Finally the experiments on gyro detection were used to test the results of detection capacitance analysis and the data was further processed.In the analysis, the error of using capacitance characterization of position change was small only when the position change was small. Among the factors that could affect the differential capacitance results, large electrode plate spacing could obtain good linearity, but would be at the expense of the loss of sensitivity. For electrode center angle and the inner and outer radius, increasing the plate area could get more favorable result after comprehensive comparison. In terms of electrode distribution, four-electrode scheme was more suitable compared with three and eight electrode scheme which could finish the signal processing without extra burden on the system. Through mathematical modeling of the detection structure and circuit, a theoretical basis for calculation of gyro and other subsequent signal processing was built. In the circuit simulation, a DC voltage signal containing information of the change in capacitance was obtained which had good linearity with the correlation coefficient of 0.99994. The experiment verified the simulation results of the finite element analysis. About the nonlinear problem that still existed, error compensation was used to perform the linear processing and the more accurate voltage-angular velocity relationship was obtained with the non-linear error reducing to 0.25377% from 5.2322%.