Papers by Author: Jun Liu

Abstract: For testing angle velocity, testing system of micromechanical gyroscope is applied widely in both military and civil areas, and it is provided with broad foreground of evolution and application, The characteristics of the application require them have high sensitivity and accuracy, under this conditions, technology development level of interface circuit reach their limits, and restricts test performance improvement of the system of micro-gyroscope. In this paper the equivalent electrical model of capacitive micro-gyroscope is established firstly, then a novel interface circuit is designed, the interface circuit include two part, driving-circuit and detecting- circuit, and the feasibility of the driving-circuit and detecting- circuit is emulated and validated by Pspice respectively. The detecting circuit of static state capacitance is come true , and theoretical accuracy of it is 10-18F.

Abstract: Pb0.97La0.02(Zr0.95Ti0.05)O3 antiferroelectric thick films were prepared on platinized silicon substrates by sol–gel methods. Films showed polycrystalline perovskite structure with a strong (100) preferred orientation. The antiferroelectric nature of the films was confirmed by the double hysteresis behaviors versus applied field. The temperature dependence of dielectric constant and loss displayed the Curie temperature was 225oC.The current caused by the polarization and depolarization of polar was detected at coupling application of electric field and temperature. The phase transition characterization could be effectively adjusted by electric field and temperature.

Abstract: When the Micro Inertial Measurement Unit is been placed randomly in the case of stationary, the sum vectors that measured by the inertial devices configured orthogonally along three axis, are constant vectors. In view of the above objective facts, a field calibration method of micro inertial measurement unit was proposed. On the base of the establishment and optimization of calibration model, all parameters to be calibrated can be obtained through the least square by the ellipsoid fitting, with the result of high-precision field calibration for micro inertial measurement unit. Finally, a filed calibration program for micro inertial measurement unit is scheduled reasonably. The experiment results show that the method has such characteristics such as easily-operation, time-saving, higher calibration accuracy, and not depending on the baseline direction and datum offered by precision instruments. Especially, it fits for inertial measurement systems which work short time and ask for high accuracy. In addition, it can also significantly increase the measurement accuracy of micro inertial measurement system in practical application.

Abstract: In this paper, We use a novel principle to detect acceleration and report how I-V characteristics and piezoresistance coefficient of AlGaN/GaN HEFT-micro-accelerometer are affected by setting different temperatures. It is shown that saturation current of device would go down if the temperature goes up, which is about 0.028mA/°C, based on the research. However, the device can work well at the temperature range of -50°C to 50°C, which indicates that it can work safely in the larger temperature range.

Abstract: By researching and investigating the structure of capacitive gyroscopes, A novel capacitive micromachined gyroscope is proposed and the structure is designed. The method of electrostatic comber drive, capacitive detection of bar structure is used for the structure, and these make the gyroscope high sensitivity. The main air damping of the drive mode and detection mode is slide film damping, it is possible to make the gyroscope achieve high Q-values at atmospheric pressure. The decoupled gyroscope is designed, too. By large numbers of simulation analysis， frequencies of the first six steps mode are gained, nature frequencies of drive mode and sense mode of gyroscope are a close match, and rationality of the structure is validated. At last, the structure encapsulated is presented.