Wheel Gyroscope Research Articles

Analysis of imperfections sensitivity and vibration immunity of MEMS vibrating wheel gyroscope

Analysis of imperfections sensitivity and vibration immunity of MEMS vibrating wheel gyroscope

A discrete-time self-clocking complex electromechanical ƩΔM gyroscope with quadrature error cancellation

In this work, a new self-clocking electromechanical sigma-delta modulator (ƩΔM) quadrature error cancellation scheme for MEMS mode-matching gyroscopes is presented. The proposed techniques allow to decompose the gyroscope sense mode into in- and quadrature-phase signals and process it with two high-order sigma-delta control loops, achieving efficient noise shaping and error suppression. Furthermore, the system was designed with a self-clocking calibration scheme to provide temperature-independent turn-on bias output. Simulation results proved its robustness, a significant improvement for linearity and achieving over 80 dB attenuation of quadrature error. The hardware implementation comprising a discrete interface circuit and a wheel gyroscope was demonstrated. Measurement results validate the inherent loop quadrature cancellation scheme and demonstrate a sub-1°/hr bias instability (BI), with 5.5X and 3X improvement of BI and angle random walk (ARW) compared with a conventional single-loop ƩΔM gyroscope system. Combined with real-time self-clocking control, it yields an improvement of turn on bias error (1800s) and output linearity, achieving 1°/h and 0.021 %, respectively.

Design of a Dual Quantization Electromechanical Sigma–Delta Modulator MEMS Vibratory Wheel Gyroscope

This paper presents a dual quantization lateral-axis capacitive electromechanical sigma–delta modulator (EM- $\Sigma \Delta {\mathrm{ M}}$ ) vibratory wheel gyroscope under mode-matched condition. A symmetric wheel gyroscope structure was designed, fabricated, and wafer-level packaged under vacuum. The EM- $\Sigma \Delta {\mathrm{ M}}$ interface loop adopts a fourth-order multifeedback and local resonator $\Sigma \Delta {\mathrm{ M}}$ noise shaping structure, taking advantage of single-bit and multibit quantization in a single-loop modulator. To evaluate the influence of quantization noise, various numbers of bits of the multibit quantizator were compared and the optimal number of bits was calculated. The interface circuit system was implemented in hardware based on a low-noise front-end application-specified integrated circuit and a back-end discrete-time EM- $\Sigma \Delta {\mathrm{ M}}$ realized in a field-programmable gate array chip. The system clock was generated using a self-clocking scheme, which allows interfacing to gyroscope with a wide range of drive frequencies. Experimental evaluation indicated that the digital gyroscope system achieved a scale factor of 2073LSB(4.1 mV)/deg/s, with a nonlinearity of 0.046%, a noise floor of 3.1 m°/s/ $\surd $ Hz within a bandwidth of 100 Hz, and a bias instability of 1.3 deg/hr. [2017-0081]

A Mode Matched Triaxial Vibratory Wheel Gyroscope with Fully Decoupled Structure.

To avoid the oscillation of four unequal masses seen in previous triaxial linear gyroscopes, a modified silicon triaxial gyroscope with a rotary wheel is presented in this paper. To maintain a large sensitivity and suppress the coupling of different modes, this novel gyroscope structure is designed be perfectly symmetrical with a relatively large size of about 9.8 mm × 9.8 mm. It is available for differentially detecting three-axis angular rates simultaneously. To overcome the coupling between drive and sense modes, numerous necessary frames, beams, and anchors are delicately figured out and properly arranged. Besides, some frequency tuning and feedback mechanisms are addressed in the case of post processing after fabrication. To facilitate mode matched function, a new artificial fish swarm algorithm (AFSA) performed faster than particle swarm optimization (PSO) with a frequency split of 108 Hz. Then, by entrusting the post adjustment of the springs dimensions to the finite element method (FEM) software ANSYS, the final frequency splits can be below 3 Hz. The simulation results demonstrate that the modal frequencies in drive and different sense modes are respectively 8001.1, 8002.6, 8002.8 and 8003.3 Hz. Subsequently, different axis cross coupling effects and scale factors are also analyzed. The simulation results effectively validate the feasibility of the design and relevant theoretical calculation.

Design and simulation of a dual-axis sensing decoupled vibratory wheel gyroscope

The current dual-axis vibratory wheel gyroscopes are mostly designed to have merely one proof mass, so the sensing signal measured from the two axes will interfere with each other and will result in zero rate output. This study presents a novel design of dual-axis sensing decoupled vibratory wheel gyroscope. The main structure, which consisted of three proof masses, can measure the angular rate of two different axes independently. A triple-beam-shape torsional spring is used to suppress the undesired in-plane linear motion of the proof mass. A prototype gyroscope design was employed to verify the concept and the performance of the present design concept. The simulation results show that the natural frequencies of the driving mode and the dual-axis sensing modes are 4585, 4604, and 4606 Hz, respectively. It successfully demonstrates that the dual-axis sensing modes are decoupled with each other. With the driving voltage of 20 V and the quality factor of 2000, the sensitivities of the dual-axis sensing modes can reach 7.4 and 19.4 fF/°/s, respectively, and the nonlinearity of the dual-axis sensing modes are only 0.04 and 0.29% within the dynamic range of ±150°/s.

Analysis of mathematical model for micromechanical vibratory wheel gyroscope

By the sketch of structure of MVWG, the working laws of this kind of gyroscope were explained. To the aid of Euler’s Dynamics Equation, a mathematical model of the gyroscope was constructed, and then by the basic working laws of MVWG the model was simplified. Under the conditions of the three axial direction rotations and general rotation, the mathematical model was resolved. And finally by the solutions, the working laws of the gyroscope, the working disparity among all sorts of gyrations and the influences from the gyrations in the axial directions were analysed.

Dynamics of micromachined vibrating gimbal and wheel gyroscope

We deduce dynamic equations of micromachined vibrating gimbal and wheel gyroscope and give an approximate solution of enough accuracy. The comparison between the approximate solution and the solution used often in the literature is given. According to property of the approximate solution a decoupled two-axes gyroscope will be composed of two single-axes gyroscopes.