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Resonant micro-accelerometers have good properties such as the large dynamic range, the high sensitivity, the strong anti-interference ability as well as the direct digital output. A new z-axis resonant micro-accelerometer based on electrostatic stiffness is researched. The new z-axis resonant micro-accelerometer consists of a torsional accelerometer and two plane resonators. The sensing movement of the accelerometer is decoupled with oscillation of the plane resonators by electrostatic stiffness, which will benefit to improve the performance of the new z-axis resonant micro-accelerometer. The new structure is designed. The sensitive theory of the acceleration is investigated and the equation of scale factor is deduced under ideal conditions. The simulation is implemented to verify the basic principle by the Ansys and Matlab. The structure simulation results prove that the effective frequency of the torsional accelerometer and the resonator are 0.66kHz and 13.3kHz separately. And the interference modes are isolated with the effective mode apparently. The system simulation results indicate that the scale factor is 37Hz/g and the system has excellent capabilities in locking and tracking natural frequency of resonators, which proves that the basic theory is feasible.

Due to that the Doppler parameters vary according to slant and the resolution is lower using imaging algorithm of traditional pulse compression in processing raw echo data of the missile-borne synthetic aperture radar (SAR). Moreover, an algorithm is proposed to solve these problems, which is based on the fractional Fourier transform (FrFT) for missile-borne SAR imaging. Firstly, an echo signal model is built for the terminal guidance stage of the missile-borne SAR. Secondly, measure the chirp rate of the echo signal through the local optimum processing and get the optimum angles for the FrFT, and then the entire SAR image can be obtained by using FrFT with the optimum angles of the azimuth and range. Finally, the performances of the algorithms are assessed using simulated and real Radarsat-1 data sets. The results confirm that the FrFT-based missile-borne SAR processing methods provide enhanced resolution yielding both lower side lobes effects and improved target detection. The method introduced in this paper has important theoretical significance in detection and recognition for military targets and precision guidance.

We present the design, fabrication, and testing of a new silicon triaxial resonant micro-accelerometer. It is characterized by a biaxial planar resonant micro-accelerometer and a vertical resonant micro-accelerometer based on electrostatic stiffness. The biaxial resonant micro-accelerometer, which is decoupled in two sensitive directions by four pairs of decoupling beams, senses the acceleration by two pairs of tuning fork resonators with an excellent linearity and uniformity. The vertical resonant micro-accelerometer, where the sensing movement of the accelerometer is decoupled with oscillation of the plane resonators, senses the acceleration by electrostatic stiffness. Six analog self-oscillation circuits and a digital frequency measurement circuit based on FPGA are designed to control the triaxial resonant micro-accelerometer. The standard three-mask Deep Dry Silicon on Glass (DDSOG) process is used for fabrication of the triaxial decoupled resonant microaccelerometer. Experimental results demonstrate a mechanical sensitivity of 52.57Hz/g(x-axis), 51.64 Hz/g(y-axis) and 31.65 Hz/g(z-axis) and a bias stability of 0.294mg(x-axis), 0.278mg(yaxis) and 0.727mg(z-axis).