基于加速度计或陀螺仪的测姿方法均存在大角度条件下姿态角误差放大、突变问题.对大俯仰角测量,通过预置欧拉旋转法可确定冗余加速度计的布置方式,降低了俯仰角测量误差.对大俯仰角条件下的滚转角测量,提出基于角速率阈值判定的陀螺解耦测姿算法.当俯仰角速率大于设定阈值时,采用角速度投影可钳制滚转角误差的漂移;当俯仰角速率小于设定阈值时,采用角速度积分可避免角速度投影造成的姿态误差放大.通过理论推导、分析和仿真,预置欧拉旋转法能有效避免大俯仰角条件下俯仰角姿态误差放大,陀螺解耦测姿算法能在振荡环境下长时间保持滚转角精确度.

针对大迎角测姿时现有加速度计测量架构对姿态信息利用不足,以及现有杆臂处理算法残差过大的问题,提出了一种基于惯性技术的3加速度计加1陀螺仪的系统架构.该架构改进了力学编排方式,在静态条件下有效提高了大迎角测姿精度.在动态条件下基于频率阈值判决的离心加速度补偿算法能有效去除杆臂效应离心加速度项;同时双加速度计的系统构型能有效避免杆臂效应切向加速度项的误差放大.转台实验验证结果表明,静态环境下大迎角测姿精度可达到0.006°,动态环境下大迎角测姿精度可达到0.12°,有效改善了动态环境下大迎角的测姿精度.

振动环境下叠加在航姿参考系统(AHRS)加速度计敏感轴上的杆臂效应会对加速度计测姿精度造成极大的影响.本文对杆臂效应处理算法中的低通滤波法和力学补偿法进行分析.低通滤波法滤除杆臂效应会有整流误差残存.力学补偿法对杆臂效应中向心加速度项的补偿受限于陀螺测量精度,对杆臂效应中切向加速度项的补偿会因为直接对角速度微分求取角加速度造成误差激剧放大.针对低通滤波法与力学补偿法各自存在的不足,提出一种改进的杆臂效应补偿方法.对杆臂效应中的向心加速度项的补偿,设定角频率阈值作为判定值.在低于给定角频率阈值工况下采用低通滤波法,而在高于给定角频率阈值工况下采用力学补偿+低通滤波法.对杆臂效应中的切向加速度项的补偿,提出2种多加速度计构型,根据加速度计构型中各加速度计输出值,构造解析公式求解角加速度,避免直接微分法造成的误差放大.通过对改进补偿方法的理论推导、分析和仿真,并与低通滤波法和力学补偿法相对比,改进补偿方法显著地提高了杆臂效应误差补偿精度.

This paper presents a novel multi-objective parameter optimization method based on the genetic algorithm (GA) and adaptive moment estimation (Adam) algorithm for the design of a closed-loop control system for the sense mode of a Microelectromechanical systems (MEMS) gyroscope. The proposed method can improve the immunity of the control system to fabrication tolerances and external noise. The design procedure starts by deriving a parameterized model of the closed-loop of the sense mode. The loop parameters are then optimized by the GA. Finally, the ensemble of optimized loop parameters is tested by Monte Carlo analysis to obtain a robust optimal solution. Simultaneously, the Adam-least mean square (LMS) demodulator, which is appropriate for the demodulation of very noisy signals, is also presented. Compared with the traditional method, the time consumption of the design process is reduced significantly. The digital control system is implemented by the print circuit board based on embedded Field Programmable Gate Array (FPGA). The experimental results show that the optimized control loop has achieved a better performance, the system bandwidth in open-loop and optimal closed-loop control system is about 23 Hz and 101 Hz, respectively. Compared to a non-optimized closed-loop system, the bias instability reduced from 0.0015°/s to 7.52 × 10−4°/s, the scale factor increased from 17.7 mV/(°/s) to 23 mV/(°/s) and the non-linearity of the scale factor reduced from 0.008452% to 0.006156%.

Limited by the micro-electromechanical system (MEMS) fabrication technology, the in-operation drift of MEMS gyroscope which degrades measurement repeatability, accuracy, and stability has non-stationary wide-band components and a large difference between each power cycle. The drift limits the usability of MEMS gyroscope in a variety of field applications where autonomous and repeatable operation is required over a long time in harsh environmental conditions. Therefore, a novel method is proposed to compensate the drift. At first, an improved complete ensemble empirical mode decomposition is used to decompose the original signals into a series of intrinsic mode functions (IMFs), and the threshold de-noising method is adopted to filter the IMFs; then, the de-noised sub-series are reconstructed into training and testing dataset, respectively, and the bagging extreme learning machine-based model has been trained; finally, the compensation signal is predicted by the model with testing dataset, and the desired results can be obtained after compensation. The proposed method has been validated by a 9000-s in-operation experiment of CRG20 by comparing it with a typical method. The experiment demonstrated that the proposed method can enhance generalization performance and can boost compensation accuracy of the model, and the bias instability reduced from 0.0785°/s to 0.0046°/s.

This paper presents a bias drift self-calibration method for micro-electromechanical systems (MEMS) gyroscopes based on noise-suppressed mode reversal without the modeling of bias drift signal. At first, the bias drift cancellation is accomplished by periodic switching between operation mode of two collinear gyroscopes and subtracting the bias error which is estimated by the rate outputs from a consecutive period interval; then a novel filtering algorithm based on improved complete ensemble empirical mode decomposition (improved complete ensemble empirical mode decomposition with adaptive noise-CEEMDAN) is applied to eliminate the noise in the calibrated signal. A set of intrinsic mode functions (IMFs) is obtained by the decomposition of the calibrated signal using improved CEEMDAN method, and the threshold denoising method is utilized; finally, the de-noised IMFs are reconstructed into the desired signal. To verify the proposed method, the hardware circuit with an embedded field-programmable gate array (FPGA) was implemented and applied in bias drift calibration for the two MEMS gyroscopes manufactured in our laboratory. The experimental results indicate that the proposed method is feasible, and it achieved a better performance than the typical mode reversal. The bias instability of the two gyroscopes decreased from 0.0066 ° / s and 0.0055 ° / s to 0.0011 ° / s ; and, benefiting from the threshold denoising based on improved CEEMDAN, the angle random walks decreased from 1.18 × 10 - 4 ° / s 1 / 2 and 2.04 × 10 - 4 ° / s 1 / 2 to 2.19 × 10 - 5 ° / s 1 / 2 , respectively.

In order to eliminating the long-term zero bias drift of MEMS gyroscope efficiently, a multi-scale processing method is proposed by utilizing signal decomposition. At first, an improved complete ensemble empirical mode decomposition (Improved CEEMD) is used to decompose the original signal into a series of stationary modes; then the distinct sub-series are clustered based on the sample entropy, and extreme learning machine (ELM) based model is used to train the sub-series; finally, the desired results can be obtained after de-noise and compensation. To verify the method, MEMS gyroscope CRG20 has been chosen for an hour test, and the experiment shows that zero bias drift reduced from 0.0706°/s to 0.0706°/s($1-\sigma )$ within temperature range of - 40° C to 70° C.

This paper presents a novel capacitive microelectromechanical systems (MEMS) accelerometer with slanted supporting beams and all-silicon sandwich structure. Its sensing mechanism is quite similar to an ordinary sandwich-type MEMS accelerometer, except that its proof mass is suspended by a beam parallel to the {111} plane of a (100) silicon wafer. In this way, each sensing element can detect accelerations in two orthogonal directions. Four of these sensing elements could work together and constitute a 3-axis micro-accelerometer by using a simple planar assembly process. This design avoids the traditional 3-axis accelerometer’ disadvantage of possible placement inaccuracy when assembling on three different planes and largely reduces the package volume. The slanted-beam accelerometer’s performance was modeled and analyzed by using both analytical calculations and finite element method (FEM) simulations. A prototype of one sensing element was fabricated and tested. Measured results show that this accelerometer has a good bias stability 76.8 ppm (1σ, tested immediately after power on), two directional sensitivities (sensitivity angle α = 45.4°) and low nonlinearity (<0.5%) over a sensing range up to ±50 g, which demonstrates a great opportunity for future high-precision three-axis inertial measurement.

This paper describes a force rebalance and quadrature offset control method for the sense mode of silicon-on-glass z axis gyroscope operating at atmospheric pressure. Quadrature offset is an important strategy to correct the structural imperfection. The force rebalances method for the sense mode of MEMS gyroscope is used to improve the quality of sense axis. A double decoupled MEMS tuning fork gyroscope is used to carry out the experiment. The measured scale factor was 6.9 mV/°/s in a range of ±360 °/s with a nonlinearity of 0.09%. Zero bias stability of 0.7 °/h for long term measurements.

There are many disadvantages to correct the nonlinearity of the accelerometer with centrifuges such as time-consuming,high cost and so on.It is meaningful to find an alternative method to improve the production efficiency.The operating principle of the accelerometer in the ideal case is deduced,and the effects of the additional electrostatic force exerted by the carrier on the test results are analyzed.The equation on resulting in the nonlinearity is deduced by conside-ring the closed-loop balanced structural asymmetry factor.Three main factors leading to the closed-loop structural asymmetry are located: the parasitic capacitance,asymmetry of structure itself and zero deviation of the servo circuit.After analyzing the effects of these factors above,the solutions are proposed accordingly to improve the linearity of the accelerometer.Finally,the engineering nonlinear compensation method is introduced,and the compensation method consi-dering large temperature variation is also suggested.The experimental results show that this technology can increase the nonlinearity of the accelerometer by about one order of magnitude.

The traditional frequency sweeping test for the micro-mechanical gyroscope is based on some costly testing instruments,and has some defects,such as the high cost and low efficiency.A portable frequency sweeping test instrument was designed based on the field programmable gate array(FPGA).The test instrument can carry out the frequency sweeping test automatically and test the resonant frequency and quality factor,complete the direct current sweeping test by means of artificially changing the value of the direct current and draw characteristic curves in the display screen.The direct digital synthesize(DDS) technology was applied to generate the AC driving signal in the open-loop driving circuit.The least squares algorithm was applied to estimate the range of the resonant frequency so as to shorten the test time and improve the test efficiency.The result of the applying test shows that the portable test instrument can finish the frequency sweeping test fast and accurately,and the test data are in good accord with the traditional way.

This paper presents a robust optimal model of Micro Electro Mechanical Systems(MEMS) gyroscope and its design procedure.The proposed method adopts the sensitivity analysis considering the worst-case tolerance instead of statistical information about uncertainties.The genetic algorithm with the advantage of global optimization is employed.Sensitivity analysis shows the robust design is less sensitive to errors.Monte Carlo analysis is also performed,whose result indicates 88.35% of samples are acceptable.The gyroscope is fabricated using bonding and deep etching bulk micromachining process.

By analyzing the requirement of the closed-loop control for the vibratory gyroscope,the behaviour of the self-oscillation system with automatic gain control was analyzed with averaging method to achieve system stability and stable equilibrium.The theoretic analysis and experiment show that the reference voltage must be larger than a critical value;the larger the reference voltage is,the larger the signal-noise-ratio is;the system phase error will cause the resonance frequency drift and decrease the vibrating amplitude;different constants of the low pass filters result in different time to achieve the stable states.The experiment shows the frequency accuracy of the close-loop self oscillation system is about ±8ppm in 10 minutes and vibration amplitude is about 0.1% error in an hour.

A z-axis decoupled micromachined gyroscope with dual frames is designed, fabricated and tested. The robust structure considering fabrication errors is obtained by the use of optimal robustness of design and process compensation. The gyroscope is packaged in vacuum, and test results show that quality factor of driving and sensing modes are 2000 and 800, respectively. In the range of 0~2400 deg/sec, sensitivity and linearity of the fabricated gyroscope are 1 deg/sec and 0.3%, respectively.

A decoupled-sense-mode z-axis micromachined gyroscope is presented.The sense mode is restricted to be only one degree of freedom for vibration,which restrains the effect from the drive mode and reduces the undesired sense mode bias.Using double masses allows both matched natural frequencies and decoupled modes.A U-shaped beam is utilized for meeting the requirements on the degrees-of-freedom of the drive and sense modes.In order to create a high-aspect ratio structure,a Deep Reactive Ion Etching(DRIE) process is used to achieve a larger proof mass,reduce the thermomechanical noise floor and provide high sensitivity.The area of the fabricated gyroscope is 2 100 μm×2 100 μm,with a thickness of 60 μm.The gyroscope is vacuum-packaged for a high mechanical quality factor.Measured results show that the drive and sense mode quality factors are 2 000 and 1 800,respectively,and the thermomechanical noise floor is 3.76(°)/h·Hz-12.The scale factor is 21 mV/(°)·s-1 in a range of ±200(°)/s,with a full-scale nonlinearity of 1.426 %FS.The bias drift is 0.057 9(°)/s over a 1 h measurement period.

A robust design applied to microgyroscope using tolerance analysis was presented,and the optimal robust design procedure was developed.The proposed robust model was formulated through estimating the nominal values and perturbation of the objective function and constraints,considering the worst-case tolerance as the perturbation in design parameters.Automatic design procedure based on such an approach was developed for microgyroscope structure design,and it was realized in a design environment integrating device modeling and optimization.And the genetic algorithm with the advantage of global optimization was employed.A comparison of different robust designs shows that the presented method can obtain a higher quality result at a moderate computational cost.Sensitivity analyses show that the robust optimum is less sensitive to errors than the optimal design.Moreover,Monte Carlo analysis was performed to check the yield of robust design,which indicates that 88% of samples are acceptable,whereas the percentage is only 50% for the deterministic optimization.The gyroscope has been fabricated using bonding and deep reactive ion etching technique.

A robust design method applied to microgyroscope is presented which is of automation, efficiency and accuracy. The design target is to maximize the microgyroscope performance, within minimum variation of performance due to uncertainties caused by fabricating errors. Analysis of the tolerance is used to calculate the nominal value and the transmitted variation of the objective function, and the genetic algorithm with advantage of global optimization is employed for the optimal process. Compared with stochastic optimization and sensitivity analysis investigated in previous studies, proposed method in this paper can reach more accurate results with lower computational cost. Robustness analyses of optimization and robustness show robust optimum is less sensitive to errors than deterministic optimization. Also, Monte Carlo simulation is performed to check yield of robust design, and the result indicates 90% of samples are acceptable, whereas, only 50% in the deterministic optimization.

This paper reports on a robust optimal design of MEMS gyroscope. Proposed robust design method uses perturbation method, which doesn't need to calculate derivative compared with method based on sensitivity analysis, considering the worst-case tolerance instead of statistical information about uncertainties. Monte Carlo analyses of robust and deterministic optimization are also studied, and results indicate that more than 80% of the objective function samples with standard deviation 0.4μm is acceptable with respect to the robust design. System-level based on macromodels and physical level based on finite element model simulation verifications show that the MEMS gyroscope designed using presented method is acceptable.

The dynamic magneto-mechanical behaviors in a type of iron-nickel-based ferromagnetic alloy with constant elasticity were investigated as a function of both the DC bias magnetic field (H-dc) and the frequency. The rectangular plate-like samples were excited to vibrate at a half-wavelength, longitudinal resonance by an AC magnetic field superimposed with various H-dc. The experimental results found that the strain coefficient at resonance reached 819.34 nm/A and the effective mechanical quality factor (Q(m)) was greater than 2000. The ratio of the maximum variation of the Young's modulus over H-dc to the value of the Young's modulus at a zero bias field was only similar to 0.8 parts per thousand because of the so-called constant elasticity. The resonant strain coefficients and Q(m) are strongly dependent on H-dc, which indicates a promising potential for use in DC and quasistatic magnetic field sensing.

The working principle about peripheral circuit of tuning fork micro-machined gyroscope is introduced,as well as its basic structure and composed segments.The peripheral circuit is established aiming at the sense mechanism element.The mathematic model is created through system analysis.The system simulation is prosecuted by Matlab so as to validate the feasibility of circuit.Some advantaged analytical method can be provided for practical debugging according to the simulation result.