Performance Of MEMS Gyroscope Research Articles

Low-cost MEMS gyroscope performance improvement under unknown disturbances through deep learning-based array

The performance of low-cost Micro Electro Mechanical systems (MEMS) gyroscope severely deteriorates under unknown disturbances, such as temperature, vibration and shock. In this paper, gyroscope array based on deep learning is proposed to improve the accuracy of single gyroscope during unknown disturbances. First, the gyroscope raw data are subjected to modeling and estimation within long short-term memory (LSTM) neural network. By training the model within the LSTM network, the intricate patterns and dynamic variations present in the gyroscope data could be captured, resulting in the generation of high-quality state estimates. Furthermore, the dropout technique is introduced to finely adjust the LSTM model, with the aim of reducing overfitting risks and effectively diminishing the computational complexity of the network. Lastly, state estimates generated by the LSTM are ingeniously combined with the raw gyroscope observations, furnishing the Kalman filter (KF) with input. The simulation and experiment results demonstrate that compared with the gyroscope array based on KF and H∞, the proposed method exhibits better performance and robustness.

Feedthrough effect in MEMS gyroscopes and fully differential feedthrough cancellation method.

In the operation of MEMS gyroscopes, the feedthrough signal is inevitably introduced through the feedthrough capacitance and significantly affects the performance of MEMS gyroscopes. The common feedthrough cancellation methods highly depend on the microfabrication process and the structural symmetry of MEMS gyroscopes, which cannot effectively eliminate the feedthrough signal. In order to solve this problem, a new feedthrough cancellation method based on a fully differential configuration is proposed in this paper. The influence of the feedthrough effect is analyzed by establishing an equivalent circuit model including the feedthrough capacitance and described by the admittance diagram. Different drive and detection configurations are compared for the problem of feedthrough mismatch on different paths. Based on the theoretical analysis, a fully differential feedthrough cancellation scheme combined with two inverse feedthrough cancellation circuits is proposed. The deviation of feedthrough signal caused by the asymmetry of two differential paths can be adjusted by the two inverse feedthrough cancellation circuits. The fully differential configuration can further increase the drive force and suppress the common mode errors. The experimental results indicate that the feedthrough signal is suppressed in a large degree by the designed feedthrough cancellation method. The feedthrough level is reduced by 50.53 dB, and the amplitude of the effective signal increases from 4.10 to 9.46 dB. The signal-to-noise ratio has an improvement of 212.48% than that before feedthrough cancellation. The proposed feedthrough cancellation method can significantly reduce the interference of feedthrough signals on the effective signal, effectively improving the signal quality of MEMS gyroscopes.

Automatic feedthrough cancellation methods for MEMS gyroscopes

The feedthrough effect can significantly affect the performance of MEMS gyroscopes and even lead to device failure. In order to address the inevitable problem of feedthrough capacitance caused by microfabrication process and circuit structure, two automatic feedthrough cancellation solutions are proposed based on the analysis of the feedthrough effect. Firstly, an equivalent feedthrough model is established for MEMS gyroscopes. Then, through theoretical derivation and model simulation, various influences of feedthrough effect are analysed, and the critical value of feedthrough capacitance is calculated to achieve better compensation effects. For feedthrough capacitance greater than the critical value, a feedthrough cancellation method utilizing AD5231 digital potentiometer for generating an inverse signal is designed. For the situation of feedthrough capacitance less than the critical value, a feedthrough cancellation method based on pure digital circuit calculation is proposed. The experimental results show that the method of utilizing digital potentiometer effectively reduces the feedthrough level from −17.46 dB to −32.75 dB, and the method of utilizing pure digital circuit calculation compensates the feedthrough signal of 100.04 mV to almost zero (2.44 mV) within the range of ADC sampling accuracy. These two methods can accurately and quickly suppress feedthrough signal to improve the detection performance of MEMS gyroscopes, and are expected to meet the needs of future mass production. In addition, they can be widely applied to various MEMS devices that require feedthrough cancellation.

Effects of PLL Architecture on MEMS Gyroscope Performance

Effects of PLL Architecture on MEMS Gyroscope Performance

Effects of both the drive- and sense-mode circuit phase delay on MEMS gyroscope performance and real-time suppression of the residual fluctuation phase error

This work analyses circuit phase delay for carrier-modulation MEMS capacitive gyroscopes. The temperature-dependent circuit phase delay is a major source of gyroscope output drift, which deteriorates the gyroscope bias instability (BI) and angle random walk (ARW). Effects of both drive-mode and sense-mode circuit phase delay on gyroscope performance when using different signal extraction architectures are analyzed in detail. The online suppression method which combines the so-called modified double sideband (MDSB) extraction architecture in the gyroscope drive mode and closed-loop force-rebalance loop in the sense mode can eliminate the impact of residual fluctuation error of circuit phase delay in real time. When drive-mode circuit phase delay equivalently varies from −20° to 20°, using MDSB decreases the fluctuation of the open-loop zero-rate output (ZRO) by 70% compared to using double sideband (DSB) and by 99.7% with respect to using single sideband (SSB). Meanwhile, improvement for the closed-loop ZRO using MDSB is 92.48% and 94% compared to cases using DSB and SSB, respectively. Furthermore, when the equivalent circuit phase delay of the sense-mode alters from −20° to 20°, ZRO variation for the gyroscope with force rebalanced sense loop and quadrature stiffness nulling loop decreases by 80% in contrast to the case with open loop, which demonstrates the effectiveness of online suppression for circuit phase delay of both the drive-mode and sense-mode. Using the online suppression method, the gyroscope has achieved a BI of 0.16° h−1 and ARW of 0.011° (√h)−1. Furthermore, using the MDSB in the drive mode obtains the best stability compared to using the DSB and SSB as the temperature changes.

Got to split

got to split

Relationship Between Zero-Rate Output and the MEMS Element in a Closed-Loop System

This paper analyzes how zero-rate output (ZRO) arises in the response signal of a MEMS gyroscope. ZRO challenges the performance of MEMS gyroscopes, and in order to avoid it by design, knowledge of its cause is important. In this paper, the most relevant error sources are analyzed at the signal path level, which is a more general approach than focusing on specific designs. An analysis underscores the general understanding, which is necessary in order to improve the overall performance and the robustness of MEMS gyroscopes. A method to approximate nonlinear models through the coupling of two linear models is presented. The quality of the approximation and the necessary preconditions are shown. The theoretical results are verified by numerical simulations. An extension of the model to other nonlinearities is also discussed. With this approximation, the signal paths in the system, and especially those caused by the nonlinearity, lend themselves to an analysis.

A gyroscope fabrication method for high sensitivity and robustness to fabrication tolerances

MEMS gyroscopes have favorable characteristics, including small size, high throughput, and low cost. The performance of MEMS gyroscopes depends on the displacement sensitivity of the capacitors. In this paper, we describe the fabrication of 300-µm-thick gyroscopes that can provide high displacement sensitivity and are robust to fabrication tolerances, i.e. deep reactive ion etch (DRIE) rate uniformity. When thick structures are perforated using DRIE to achieve high-aspect-ratio features, footing is commonly observed. However, we describe a fabrication method that circumvents problems associated with footing and side-wall etching, so that the gyroscopes can have uniform dimensions and small variations across the wafer. Using a post-fabrication translation approach, the position of capacitors is modified following DRIE, and the gap in the gyroscopes can be reduced to 3 μm, which leads to an aspect ratio of 100. Using this method, we fabricated MEMS gyroscopes that can overcome the DRIE aspect ratio limit and have capacitors with higher sensitivities than those of other gyroscopes, which typically employ substrates that are less than 100 µm thick. The gyroscope had a resonant frequency of 9.91 kHz, a quality factor of 2500 and a sensitivity of 23 mV/[deg/s].

Research on Optimal Weight Choice of Multi-MEMS Gyroscope Data Fusion

The performance of MEMS gyroscope is crucial to its application, and the zero-bias stability is the main characteristic parameter of gyroscope performance. When fusing several outputs of similar MEMS gyroscope, we often use the weighted mean method. The weight has great influence on the fusing result. In this paper, the optimal weight choice used in the fusion of Multi-MEMS gyroscope data is derived based on multivariate numerical theory. Experimental results show that after simulating multi-MEMS gyroscope data fusion on the measurement result of several gyroscopes, the zero-bias stability will effectively improve.

Temperature and Humidity Effects on MEMS Vibratory Gyroscope

MEMS vibratory gyroscopes are increasingly used in applications ranging from consumer electronics to aerospace and are now one of the most common MEMS products after accelerometers. Despite their widespread use, the performance of MEMS gyroscopes in harsh environments is still under question. While some studies have been conducted to understand the temperature dependent performance of MEMS gyroscopes, the effects of sustained exposure to temperature combined with other harsh environment stresses have not been well researched. Thus, it is necessary to quantify MEMS vibratory gyroscope performance under such conditions. This paper will focus on the combined effects of temperature and humidity only. Performance of the MEMS vibratory gyroscope will be evaluated over time at high temperature and high humidity conditions by conducting an aging test on a COTS (commercial of the shelf) single axis MEMS vibratory gyroscope having an operating temperature range from −40°C to 80°C. The gyroscope sensor will be exposed to 60 °C and 90% RH (Relative humidity) for 500 hours. In-situ data will be monitored to track any shifts in device output. Any permanent changes in the output signal will be traced back to their fundamental root cause damage mechanism.

Videometrics-based Detection of Vibration Linearity in MEMS Gyroscope

MEMS gyroscope performs as a sort of sensor to detect angular velocity, with diverse applications in engineering including vehicle and intelligent traffic etc. A balanced vibration of driving module excited by electrostatic driving signal is the base MEMS gyroscope's performance. In order to analyze the linear property of vibration in MEMS Gyroscope, a method of computer vision measuring is applied with the help of high-speed vidicon to obtain video of linear vibration of driving module in gyroscope, under the driving voltage signal of inherent frequency and amplitude linearly increasing. By means of image processing, target identifying, and motion parameter extracting from the obtained video, vibration curve with time variation is acquired. And then, linearity of this vibration system can be analyzed by focusing on the amplitude value of vibration responding to the amplitude variation of driving voltage signal.

Performance and Reliability of MEMS Gyroscopes and Packaging at High Temperatures

Elevated temperatures can significantly affect the performance and reliability of MEMS gyroscope sensors. A MEMS vibrating resonant gyroscope measures angular velocity via a displacement measurement which can be on the order on nanometers. High sensitivity to small changes in displacement causes the MEMS Gyroscope sensor to be strongly affected by changes in temperature which can affect the displacement of the sensor due to thermal expansion and thermomechanical stresses. Analyzing the effect of temperature on MEMS gyroscope sensor measurements is essential in mission critical high temperature applications, such as inertial tracking of the movement of a fire fighter in a smoke filled indoor environment where GPS tracking is not possible. In this paper, we will discuss the development of the high temperature package for the tracking application, including the characterization of the temperature effects on the performance of a MEMS gyroscope. Both stationary and rotary tests were performed at room and at elevated temperatures on 10 individual single axis MEMS gyroscope sensors.

2D16 Analysis on Effects of Design Variable Uncertainty on the Performance of MEMS Gyroscope Based on Sample Statistics

2D16 Analysis on Effects of Design Variable Uncertainty on the Performance of MEMS Gyroscope Based on Sample Statistics