Quartz Flexible Accelerometer Research Articles

Research on high-resolution capacitance detection circuit based on T-type network

Abstract The capacitance detection circuit is a key component of the servo circuit of the quartz flexible accelerometer, which needs to ensure high-precision capacitance detection. The small capacitance change of the quartz flexible accelerometer pendulum will be affected by the noise of each device in the servo loop. To solve this problem, we design a single carrier modulation and demodulation capacitance detection circuit based on a T-type network from the capacitance detection model of a quartz flexible accelerometer. We established a circuit noise model, quantitatively analyzed the noise of the entire capacitance detection circuit from the theoretical level, and obtained the equivalent capacitance noise of the circuit. The rationality and effectiveness of the high-precision capacitance detection circuit are verified by theoretical calculation. We also verify the accuracy of the theoretical calculation through simulation and obtain the signal-to-noise ratio of the circuit. Finally, we prove that the scheme is a high-precision capacitance detection scheme.

Study on the influence of pendulum convex plate on the partial value of quartz flexible accelerometer

The partial value is an essential performance index for assessing the stability of quartz flexible accelerometers. By analyzing the structure of the quartz flexural accelerometer and the impact of the pendulum convex plate, the influence of the convex plate on the partial value of the accelerometer is studied by theoretical derivation and modeling simulation methods. The results show that the barycentric coordinate shifts by approximately 10.7678 × 10-12 µm with the change of the coplanarity of the convex plate, which causes mechanical zero position errors, increases the partial value, and affects the stability of the quartz flexural accelerometer. Therefore, the coplanarity of the convex plate should be maintained at ≤0.3 µm and the partial value should be within the error range of ≤ |±2| mg and provide improvement measures to establish a basis for further improving the stability of the quartz flexible accelerometer.

Fault diagnosis of accelerometer servo circuit output saturation based on feature electrical parameters extraction

The servo circuit of quartz flexible accelerometer is an extremely vital microelectronic device in inertial system. The paper introduces the traditional analysis process about output saturation fault of accelerometer servo circuit. For the shortcomings of traditional analysis methods, a fault diagnosis method based on feature electrical parameters extraction is proposed. According to the fault phenomenon, combined with the modular characteristics of hybrid integrated circuits, the feature electrical parameters of fault modes are extracted, and the fault modes' judgment basis is set. By the judgment results of the feature electrical parameters of the fault circuit, the circuit with output saturation fault caused by the electrical damage to the differential capacitance detector and other faults can be located quickly and accurately, and it is verified by the analysis of faulty circuit samples. Targeted for these faults, the improvement measures are put forward. This analysis method improves the fault diagnosis efficiency and reliability about the accelerometer servo circuit, and has guiding significance for enhancing the success rate of the failure analysis in the hybrid integrated circuits.

A low-noise class AB amplifier fabricated by 180 nm BCD process for servo circuit of quartz flexible accelerometer

Quartz Flexible Accelerometer (QFA) system has gained extensive utilization in related navigation system due to the high precision, exceptional stability, and rapid response. The operational amplifier as the pivotal component of the analog servo circuit intricately relative to the performance of the QFA system. In this paper, the electrical mechanism of the QFA readout system and the influence of operational amplifier noise on the noise of QFA readout system is studied, a low-noise Class AB amplifier for the servo circuit of QFA readout system designed and fabricated by 180 nm BCD process, and the QFA readout system with the designed amplifier is simulated. The experimental results show that the low-noise amplifier achieved equivalent input current and voltage noise of 5.75pA/sqrt (Hz) and 12.7nV/sqrt (Hz) separately. Simulation results shows the designed QFA servo circuit has achieved resolution of 35 μ g and noise of 2.1 μ g/sqrt (Hz) @1Hz.

The Output Nonlinear Mechanism and the Compensation Method of Digital Closed-Loop Quartz Flexible Accelerometer

The Output Nonlinear Mechanism and the Compensation Method of Digital Closed-Loop Quartz Flexible Accelerometer

Mechanical model analysis and reliability design approach of Quartz Flexible Accelerometer under fractured state

AbstractCurrently, the Quartz Flexible Accelerometer (QFA) mounted for the applications working in high acceleration environment are suffering from the fracture of the flexible beams under external acceleration shock. This paper presents the mechanical model and reliability design approach of QFA to maintain the measuring ability under a fractured state. The structural parameters changed significantly in the mechanical model under a fractured state compared to those in the original model. A modified structure to maintain the measuring ability of QFA under a fractured state is designed with the reference of the sensitive module in Electrostatic Suspended Accelerometer (ESA). The corresponding close‐loop system is corrected and discretised to ensure the stability requirements of the mechanical model. A static experiment is conducted to prove the effectiveness of the proposed model by a prototype QFA with completely fractured flexible beams. The result shows helpful on the preliminary research for QFA with the similar sensitive structure to ESA.

Study on driving noise of quartz flexible accelerometer torquer

The distributed capacitance inside the quartz flexible accelerometer (QFA) coupled the high frequency voltage excitation signal in the differential capacitance detection circuit to the torquer coil, and superimposes the torquer driving current to form the driving noise. In this study, the values of the distributed capacitance inside the QFA were simulated. According to the formation mechanism of the QFA driving noise, the equivalent circuit model of the driving noise is established, and the driving noise characteristics of the detection circuit with single excitation and double excitation source are analyzed. The theoretical and experimental results show that the electric field coupled driving noise transmission system is a first-order system with high-pass characteristics. The driving noise of the single excitation detection circuit is larger than that of the dual excitation detection circuit (DEDC), and the DEDC can reduce the driving noise by 39.77% when the QFA shell is grounded. The equivalent acceleration of the electric field coupled driving noise is between tens of μg to hundreds of mg, which is one of the important noise sources that affect the measurement accuracy of the QFA. A measure was proposed to suppress the high-frequency driving noise by adding a low-pass filter after the sampling output of the driving current, which can reduce the driving noise to 1.85 μg and effectively reduce the influence of the driving noise on the measurement accuracy of the QFA.

Precise preparation of quartz pendulous reed by using picosecond laser modification assisted wet etching

The Quartz pendulous reed is the core part of the quartz flexible accelerometer. The current quartz pendulous reed forming technology has shortcomings, such as poor processing quality and high production cost. In this paper, picosecond laser modification assisted wet etching technology is proposed to prepare quartz pendulous reed. The modification mechanism of fused silica induced by picosecond laser was investigated. Different from the network structure changes caused by femtosecond laser, mechanical damage is the main form of picosecond laser modification. The mapping among etching time, etching temperature and HF solution concentration were studied by using the control variable method. The proposed picosecond laser assisted wet etching technology has the advantages of high dimensional accuracy, good edge quality, low residual stress, and high efficiency.

Analysis of Noise-Detection Characteristics of Electric Field Coupling in Quartz Flexible Accelerometer

The internal electric field coupling noise of a quartz flexible accelerometer (QFA) restricts the improvement of the measurement accuracy of the accelerometer. In this paper, the internal electric field coupling mechanism of a QFA is studied, an electric field coupling detection noise model of the accelerometer is established, the distributed capacitance among the components of the QFA is simulated, the structure of the detection noise transfer system of different carrier modulation differential capacitance detection circuits is analyzed, and the influence of each transfer chain on the detection noise is discussed. The simulation results of electric field coupling detection noise show that the average value of detection noise can reach 41.7 μg, which is close to the effective resolution of the QFA, 50 μg. This confirms that electric field coupling detection noise is a non-negligible factor affecting the measurement accuracy of the accelerometer. A method of adding a high-pass filter to the front of the phase-shifting circuit is presented to suppress the noise of electric field coupling detection. This method attenuates the average value of the detected noise by about 78 dB, and reduces the average value of the detected noise to less than 0.1 μg, which provides a new approach and direction for effectively breaking through the performance of the QFA.

Drift Mechanism and Gain Stabilization of Digital Closed-Loop Quartz Flexible Accelerometer in Start-Up Performance

In this paper, the performance drift of digital closed-loop quartz flexible accelerometer (QFA) in start-up period is attributed to the heating of the feedback circuit and coil. Compared to the drift compensation by temperature model which is built by statical rule, the gain stabilization of closed-loop channel is an essential and direct method to restrain the drift. In this paper, a high accurate current detection circuit is designed to evaluate the parameters drift and to stabilize the gain of the feedback channel. A stability experiment is conducted to prove the efficiency of the proposed stabilization strategy. The result shows that the stability of output in start-up period improves by 37.6% at most. Therefore, the proposed stabilization strategy can effectively improve the start- up performance of QFA, which could be promoted to other sensors whose performance suffer from the drift of the channel.

Temperature compensation for quartz flexible accelerometer based on nonlinear auto-regressive improved model

Temperature variation is an important factor affecting the performance of Quartz flexible accelerometer (QFA). Performance deterioration of QFA degrades the navigation accuracy of inertial navigation system (INS). Normally dramatic change in temperature causes both thermal effect and severe creep effect on the performance of QFA. Previous papers have proved that part of errors caused by thermal effect can be restrained through simple temperature compensation. However, error caused by severe creep effect is seldom considered. In this paper, creep effect and thermal effect in QFA are detailed analyzed, respectively. Furthermore, based on the analysis of thermal effect and creep effect, the novel temperature model based on nonlinear auto-regressive with external input (NARX) improved by wavelet transform (WT) is proposed to address the retardation problem caused by thermal effect. Creep error causing the ruleless deformation of QFA’s structure is separated from overall errors, and only the thermal error whose effect has strong relationship with temperature is compensated by proposed model. Moreover, a 4-point dumpling experiment in temperature control oven is conducted to train and verify the proposed temperature model. The result of the comparative experiments shows that the performance of proposed method is the best among the comparative models. The compensation result based on proposed method improves stability of 1 g output from 776 to 14.6 µg. The proposed temperature compensation method improves the performance of QFA effectively and feasibly, which could be promoted to other applications of INS in temperature changing environment.

Temperature drift compensation of fiber strapdown inertial navigation system based on GSA-SVR

The fiber strapdown inertial navigation system (INS) has been widely utilized in aircraft, autonomous driving, robotics, and other fields due to the rapid growth of fiber technology. The core components of INS, the fiber optic gyroscope (FOG) and quartz flexible accelerometer (QFA), are prone to affected by the environmental temperature variation. The traditional temperature drift compensation method requires a considerable time to calibrate each inertial sensor individually. But after the six inertial sensors are integrated, the temperature environment inside the INS will become more complex. As a result, this device-level method has an unsatisfactory effect in the practical application of INS. Furthermore, the traditional method ignores the fact that the temperature drift characteristics of FOG are not the same at different working states. To solve the above problems, we propose a novel temperature drift compensation method of INS based on gravitational search algorithm (GSA) tuning support vector regression (SVR). The startup state and stable working state are modeled independently based on the FOG's features. Without adding additional thermometers to the inertial sensors, the temperature field is constructed by making full use of the information provided by the built-in thermometer of six inertial sensors. The experimental results verify the effectiveness of our method during different working states. And compared with the traditional polynomial fitting method, our method has better performance in the navigation experiment, the navigation accuracy increased by more than 50%.

Cold Starting Temperature Drift Modeling and Compensation of Micro-Accelerometer Based on High-Order Fourier Transform.

The traditional temperature modeling method is based on the full heating of the accelerometer to achieve thermal balance, which is not suitable for the cold start-up phase of the micro-accelerometer. For decreasing the complex temperature drift of the cold start-up phase, a new temperature compensation method based on a high-order Fourier transform combined model is proposed. The system structure and repeatability test of the micro digital quartz flexible accelerometer are provided at first. Additionally, we analyzed where the complex temperature drift of the cold start-up phase comes from based on the system structure and repeatability test. Secondly, a high-order temperature compensation model combined with K-means clustering and the symbiotic organisms search (SOS) algorithm is established with repeatability test data as training data. To verify the proposed temperature compensation model, a test platform was built to transmit the measured values before and after compensation with the proposed Fourier-related model and the other time-related model, which is also a model aiming at temperature compensation in the cold start-up phase. The experimental results indicate that the proposed method achieves better compensation accuracy compared with the traditional temperature compensation methods and the time-related compensation model. Furthermore, the compensation for the cold start-up phase has no effect on the original accuracy over the whole temperature range. The stability of the accelerometer can be significantly improved to about 30 μg in the start-up phase of different temperatures after compensation.

Research on the function failure of accelerometer servo circuit caused by hydrolysis and corrosion

This paper studied the function failure of a quartz flexible accelerometer servo circuit manufactured by a thick-film hybrid integrated process. The circuit adopts the epoxy glue bonding process of the metal shell and the ceramic cover plate to encapsulate, and it is a non-airtight package. After the circuit is powered on, the quiescent current output is abnormal, and the DC voltage output is constant high potential, the acceleration detection function cannot be realized. In response to this phenomenon, the fault tree method is used to locate the failure location, and the fault is located at the abnormal function of the differential capacitor voltage converter chip. Using microscopic analysis and characterization methods, it can be seen that the hydrolysis and corrosion of the surface of differential capacitance-to-voltage converter chip causes leakage in the active area inside the chip, leads to the function failure of the circuit. The above research is of great significance to the design, storage and application of non-hermetic hybrid integrated circuits.

Research on typical failure modes of hybrid integrated quartz flexible accelerometer servo circuit caused by multi-layer ceramic capacitors

The quartz flexible accelerometer servo circuit is one of the key components in the inertial measurement system, and the multi-layer ceramic capacitor is an important electronic component in the quartz flexible accelerometer servo circuit. This paper introduced the typical failure modes of hybrid integrated quartz flexible accelerometer servo circuit caused by multi-layer ceramic capacitors. These phenomena are analysed and studied using the circuit failure mode matching method, and improvements are proposed. The measures are of guiding significance for improving the failure analysis technology and enhancing the reliability of hybrid integrated circuit.

Research on temperature error compensation method of vehicle-mounted laser gyro SINS

In order to solve the problem that the measurement accuracy of vehicle-mounted laser gyro strapdown inertial navigation system (SINS) is affected by the temperature change, a temperature error compensation method which can adapt to the full temperature environment is proposed. Based on the phenomenon that the temperature of the inertial sensor is still rising when the temperature of the temperature control box is kept, a continuous temperature change experiment is designed. Then, Pearson correlation analysis of the output of laser gyro and quartz flexible accelerometer with temperature, temperature rate and temperature gradient has been carried out. Based on that, the temperature error models of gyro and accelerometer are constructed, and the temperature compensation method based on polynomial model is proposed. The results show that this method could compensate the temperature error of the laser gyro and the quartz flexible accelerometer effectively, and the zero-bias stability of them are both improved, especially the zero-bias stability of the accelerometer is improved by at least one order of magnitude, the accuracy of inertial measurement in full temperature environment is improved effectively.

Temperature Hysteresis Mechanism and Compensation of Quartz Flexible Accelerometer in Aerial Inertial Navigation System.

Strap-down inertial navigation systems (INSs) with quartz flexible accelerometers (QFAs) are widely used in many conditions, particularly in aerial vehicles. Temperature is one of the significant issues impacting the performance of INS. The variation and the gradient of temperature are complex under aerial conditions, which severely degrades the navigation performance of INS. Previous work has indicated that parts of navigation errors could be restrained by simple temperature compensation of QFA. However, the temperature hysteresis of the accelerometer is seldom considered in INS. In this paper, the temperature hysteresis mechanism of QFA and the compensation method would be analyzed. Based on the fundamental model, a comprehensive temperature hysteresis model is proposed and the parameters in this model were derived through a temperature cycling test. Furthermore, the comparative experiments in the laboratory were executed to refine the temperature hysteresis model and to verify the effectiveness of the new compensation method. Applying the temperature hysteresis compensation in flight condition, the result shows that the position error (CEP) is restrained from 1.54 nmile/h to 1.29 nmile/h. The proposed temperature hysteresis compensation method improves the performance of INS effectively and feasibly, which could be promoted to other applications of INS in similar temperature changing environment correspondingly.

High Precision Tri-Axial Quartz Flexible Accelerometers Resolution Measurement Method Based on Tri-Axial Turntable

Aiming at the high requirements of the experimental equipment for the measurement of high precision quartz flexible accelerometer resolution, the gravity measured by high precision tri-axial accelerometers was subdivided by the tri-axial turntable. Tri-axial quartz flexible accelerometers resolution measurement model was established and general mathematical expression for the resolution measurement was derived. Based on the mathematical expression, the effective angle range that satisfied the measurement condition was given out. Besides, the tri-axial quartz flexible accelerometers resolution measurement process was designed. Within the effective angle range, numerical simulations were performed and the simulation results showed that: the proposed method can theoretically measure tri-axial quartz flexible accelerometers of which the resolution was about 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−6</sup> g. Then the tri-axial quartz flexible accelerometers resolution repetitive measurement experiments were carried out and the experimental results illustrated that: the difference between the measured value with the theoretical value is within <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1~\mu \text{g}$ </tex-math></inline-formula> , which met the requirements for use. In addition, the resolution of tri-axial quartz flexible accelerometers can be measured at one time based on the designed process, demonstrating that the proposed method was valid.

The Estimation and Compensation of the Loop-Parameter-Drifting in the Digital Close-Loop Quartz Flexible Accelerometers

There have been increasing demands for the long-term performance retention of the Quartz Flexible Accelerometers (QFA), extensively employed in the Inertial Navigation System (INS). Considering the convenience of conducting the parameter identification and control algorithm, the Digital Close-Loop QFA (Digital-QFA) is established to improve the long-term performance. Based on the model of the entire close-loop system, the interfering factors relating to time are analyzed in detail, both in the forward channel and the feedback channel. Two schedules are proposed to estimate the gain variation, utilizing the modulating signal and the feedback signal separately. According to the reference gain settings in ideal conditions, the forward and the feedback gain drifting of the system are calibrated online through the adjustment of the digital controller and the reference voltage of the DA-chip, separately. The simulation experiments show that about 90.26% of the gain-drifting could be estimated and about 87.56% of the output error of the accelerate could be restrained. Consequently, the proposed schedules could promote the long-term stability of the Digital-QFA significantly.

Development of airborne gravity gradiometer based on a quartz flexible accelerometer

Acta Geologica Sinica - English EditionVolume 93, Issue S1 p. 352-364 Session 9: Emerging techniques for deep earth explorationFree Access Development of airborne gravity gradiometer based on a quartz flexible accelerometer Zhaohai Meng, Zhaohai Meng 526468457@qq.com Tianjin Navigation Instrument Research Institute, TianjinSearch for more papers by this authorYe Yang, Ye Yang Tianjin Navigation Instrument Research Institute, TianjinSearch for more papers by this authorZhong Li, Zhong Li Tianjin Navigation Instrument Research Institute, TianjinSearch for more papers by this author Zhaohai Meng, Zhaohai Meng 526468457@qq.com Tianjin Navigation Instrument Research Institute, TianjinSearch for more papers by this authorYe Yang, Ye Yang Tianjin Navigation Instrument Research Institute, TianjinSearch for more papers by this authorZhong Li, Zhong Li Tianjin Navigation Instrument Research Institute, TianjinSearch for more papers by this author First published: 31 May 2019 https://doi.org/10.1111/1755-6724.14133Citations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume93, IssueS1Special Issue: Abstracts of the International Symposium on Deep Earth Exploration and Practices, 24–26 Oct 2018, Beijing, ChinaMay 2019Pages 352-364 RelatedInformation