Performance Of Gyroscope Research Articles

Analysis and Compensation About Temperature Influence to Optical-Fiber Gyro Zero Bias

Abstract Compared to other gyro the dynamic performance of optical-fiber gyro was better and the price was cheap. Optical-fiber gyro was suit to build SINS. By the way, zero bias of optical-fiber gyro was sensitive to temperature, and the compensation technique was a hot point in INS research. According to the above situation, based on one type optical-fiber gyro, the influence mechanism about temperature to optical-fiber gyro zero bias was studied, and a test method was designed, the experiment results was analyzed, finally based on multinomial simulation a compensation math model was established, and the research result discovered that temperature was a big influence to optical-fiber gyro zero bias, and it can be fixed by a compensation math model based on multinomial simulation.

In-Orbit Performance Evaluation of a Spaceborne High Precision Fiber Optic Gyroscope

An in-orbit experiment was launched to evaluate the performance of the spaceborne high precision fiber optic gyroscopes (FOG). The three-axis in-orbit data of the FOG were analyzed using wavelet analysis method. Features of low frequency period terms and glitch noise were demonstrated. In addition, a method to extract the random noise from the in-orbit data is proposed based on the first-order difference method and the Pauta criterion. In addition, the random walk coefficient (RWC) of the FOG was calculated with the Allan variance method. Compared the ground test results, the in-orbit performance evaluation of Spaceborne High Precision Fiber Optic Gyroscope was verified.

Influence of Acousto-Optic Resonances in Electro-Optical Modulator on Fiber Optic Gyro Performance and Method for Its Compensation

The electro-optical modulator is one of the most important parts of the fiber optic gyroscope. Unfortunately, the integral implementation of the modulator has a number of undesirable effects such as parasitic amplitude modulation, phase drift, and acousto-optical resonance effects. Influence of the first two effects on the gyroscope operation has been described in a number of works, but at the moment, there are no published papers aimed at investigating the relationship between the presence of acousto-optic resonances in modulators and changes in the performance of a fiber optic gyroscope. There are several design solutions that provide damping of undesired acoustic waves in electro-optical modulators. However, the use of these solutions requires a method to estimate their effectiveness. The main purpose of the article is to describe such a method and to evaluate the correctness of its application. We also offer an additional way to reverse the effect of the mentioned resonant effects on the characteristics of the fiber gyroscope.

Sensitivity analysis of an in-plane MEMS vibratory gyroscope

This paper aims to put forward a detailed sensitivity analysis of an in-plane MEMS gyroscope with respect to various performance criteria that are very critical for use of the sensor in different applications ranging from platform stabilization to micro UAVs. Sensitivity analysis involves selecting key design parameters and critical performance criteria and studying the effect of variation of each design parameter on each of the performance criteria. The five key design parameters of the MEMS gyro are the drive stiffness kd, sense stiffness ks, drive mass md, sense mass ms and the sense damping coefficient Cs. The four critical gyro performance criteria selected are scale factor, bandwidth, resolution and dynamic range. The influence of variations in different geometric dimensions of the structure on the design parameters of the gyro is also established. The critical geometric dimensions are identified that are then suitably modified allowing faster convergence of the design to meet the desired performance specifications. This study is relevant on two counts (1) the fine tuning of the design to meet all the desired performance criteria with minimum variation in geometric dimensions and with no change in the footprint of the sensor die and (2) the influence of geometric dimensional variations induced during the fabrication of the MEMS gyro structure.

Investigation of cylindrical resonators’ damping asymmetry via analyzing Q factor circumferential distribution

High quality cylindrical resonators are extremely important to guarantee the performance of cylindrical vibratory gyroscope. Cylindrical resonators’ damping asymmetry is one of the major sources which result in the gyroscope’s drift. In this paper, the method of evaluating damping asymmetry based on the Q factors of the damping axes is proposed. The dynamic model of cylindrical resonators is established to analyze the Q factor’s variation under the effect of mode superposition. The weakness of measuring Q factors by amplitude-frequency response analysis is figured out. Theoretical calculation analysis based on amplitude-frequency response is also carried out to investigate the laws of Q factor circumferential distribution in detail. Theoretical results show that the Q factor circumferential distribution is influenced by the frequency difference, Q factor difference and the angle difference between damping axes and frequency axes. Furthermore, the Q factors of the damping axes can be obtained from the Q factor circumferential distribution under certain conditions when the frequency difference is relatively large. The Q factor circumferential distribution will be almost the same to the real Q factor distribution of the cylindrical resonator when the frequency difference is small enough. Furthermore, the Q factors and locations of the damping axes are able to be acquired more easily. Experiments of amplitude-frequency response analysis are also set up to validate the theoretical analysis results, from which damping asymmetry and damping axes of the cylindrical resonator can be identified.

Influences of optical-spectrum errors on excess relative intensity noise in a fiber-optic gyroscope

The excess relative intensity noise (RIN) generated from broadband sources degrades the angular-random-walk performance of a fiber-optic gyroscope dramatically. Many methods have been proposed and managed to suppress the excess RIN. However, the properties of the excess RIN under the influences of different optical errors in the fiber-optic gyroscope have not been systematically investigated. Therefore, it is difficult for the existing RIN-suppression methods to achieve the optimal results in practice. In this work, the influences of different optical-spectrum errors on the power spectral density of the excess RIN are theoretically analyzed. In particular, the properties of the excess RIN affected by the raised-cosine-type ripples in the optical spectrum are elaborately investigated. Experimental measurements of the excess RIN corresponding to different optical-spectrum errors are in good agreement with our theoretical analysis, demonstrating its validity. This work provides a comprehensive understanding of the properties of the excess RIN under the influences of different optical-spectrum errors. Potentially, it can be utilized to optimize the configurations of the existing RIN-suppression methods by accurately evaluating the power spectral density of the excess RIN.

Dynamic characteristics of resonant vibratory gyroscopes based on the damped Mathieu equation

PurposeThis paper aims to develop resonant vibratory gyroscopes for high sensitive detection. The dynamic characteristics of resonant vibratory gyroscopes are investigated.Design/methodology/approachFirstly, the working principle and the dynamic output characteristics of the resonant vibratory gyroscope could be described by the damped Mathieu equation. Moreover, an approximate analytical method based on the small parameter perturbation has been used for the purpose of investigating the approximate solution of the damped Mathieu equation. Finally, to verify the feasibility of the approximate analytical method of the damped Mathieu equation, dynamic output characteristics’ experiments of the resonant vibratory gyroscope are built.FindingsThe theoretical analysis and numerical simulations show that the approximate solution of the damped Mathieu equation is close to the dynamic output characteristics of the resonant vibratory gyroscope. On the other hand, it is concluded from the tested result that there exists a correlation between the theoretical curve and the experimental data processing result, meaning the damped dynamics analytical method is effective in building resonant vibratory gyroscopes.Originality/valueThis paper seeks to establish a foundation for optimizing and testing the performance of the resonant vibratory gyroscope. To this end, the approximate analytical method of the damped Mathieu equation was discussed. The result of this research has proved that the dynamic characteristics based on the damped Mathieu equation is an effective approach and is instructional in the practical resonant sensor design.

Development of characteristics measurement system for the micro-wall of flexible joints

Characteristics of the micro-wall of flexible joints seriously impact the performance of gyro. Hence, measurements of these characteristics become very important. The present study carries out a system to measure the characteristics, including the stiffness and thickness, of the micro-wall of flexible joints. The force sensor deemed as a core component is mainly expounded in the paper. It is developed based on the principle of resistance strain gauge and good performance is shown on measuring the stiffness and the thickness. The measurement accuracy is calculated though repeated experiments and measurement theory and results are elaborated. The measurement results help to reveal the rule of structural design so as to enhance the performance of gyro. Finally, some improvements of this measurement system are proposed for further applications.

Design, Fabrication, and Modeling of a Novel Dual-Axis Control Input PZT Gyroscope.

Conventional gyroscopes are equipped with a single-axis control input, limiting their performance. Although researchers have proposed control algorithms with dual-axis control inputs to improve gyroscope performance, most have verified the control algorithms through numerical simulations because they lacked practical devices with dual-axis control inputs. The aim of this study was to design a piezoelectric gyroscope equipped with a dual-axis control input so that researchers may experimentally verify those control algorithms in future. Designing a piezoelectric gyroscope with a dual-axis control input is more difficult than designing a conventional gyroscope because the control input must be effective over a broad frequency range to compensate for imperfections, and the multiple mode shapes in flexural deformations complicate the relation between flexural deformation and the proof mass position. This study solved these problems by using a lead zirconate titanate (PZT) material, introducing additional electrodes for shielding, developing an optimal electrode pattern, and performing calibrations of undesired couplings. The results indicated that the fabricated device could be operated at to perform dual-axis actuations and position measurements. The calibration of the fabricated device was completed by system identifications of a new dynamic model including gyroscopic motions, electromechanical coupling, mechanical coupling, electrostatic coupling, and capacitive output impedance. Finally, without the assistance of control algorithms, the “open loop sensitivity” of the fabricated gyroscope was 1.82 μV/deg/s with a nonlinearity of 9.5% full-scale output. This sensitivity is comparable with those of other PZT gyroscopes with single-axis control inputs.

Structural Analysis of Disk Resonance Gyroscope.

In this paper, we present two design methods to improve the performance of disk resonator gyroscope (DRG), including decreasing the frequency split and increasing the quality factor (Q). The structure parameters, which can affect the frequency split and Q value were concluded with the help of the FEM software. Meanwhile, devices with different parameters were designed, fabricated, and tested, and the experimental result was in accordance with the simulation. With the proposed methods, the DRG was selected with a high Q value and a low frequency split to satisfy the demand of high performance. The weakness and future works were pointed at last.

The effect of broadened linewidth induced by dispersion on the performance of resonant optical gyroscope

Anomalous dispersion enhancement physical mechanism for Sagnac effect is described by special relativity derivation, and three kinds of definitions of minimum detectable angular rate of resonance optical gyroscope (ROG) are compared and the relations among them are investigated. The effect of linewidth broadening induced by anomalous dispersion on the sensitivity of ROG is discussed in this paper. Material dispersion-broadened resonance linewidth deteriorates the performance of a passive ROG and dispersion enhancement effect, while the sensitivity of a structural dispersion ROG is enhanced by two orders of magnitude even considering the dispersion-broadened resonance linewidth.

Temperature Dependence of Faraday Effect-Induced Bias Error in a Fiber Optic Gyroscope.

Improving the performance of interferometric fiber optic gyroscope (IFOG) in harsh environments, such as magnetic field and temperature field variation, is necessary for its practical applications. This paper presents an investigation of Faraday effect-induced bias error of IFOG under varying temperature. Jones matrix method is utilized to formulize the temperature dependence of Faraday effect-induced bias error. Theoretical results show that the Faraday effect-induced bias error changes with the temperature in the non-skeleton polarization maintaining (PM) fiber coil. This phenomenon is caused by the temperature dependence of linear birefringence and Verdet constant of PM fiber. Particularly, Faraday effect-induced bias errors of two polarizations always have opposite signs that can be compensated optically regardless of the changes of the temperature. Two experiments with a 1000 m non-skeleton PM fiber coil are performed, and the experimental results support these theoretical predictions. This study is promising for improving the bias stability of IFOG.

Ball-disk rotor gyroscope adaptive quick-start technique

Rotating speed is a critical parameter affecting the performance of rotor gyroscopes. Rotor gyroscopes must operate at the rated rotating speed. To shorten the start time of the ball-disk rotor gyroscope, this paper presents a new design of the drive system for a ball-disk rotor gyroscope. The drive system is monitored by a microcontroller. First, the microcontroller generates a sine pulse width modulation signal to drive the permanent magnet rotor. Second, the position of the rotor is detected according to the back electromotive force in the non-energized coil. Third, a piecewise closed-loop control algorithm is implemented to keep the angular acceleration of the rotor within the safe range automatically during the acceleration process and when running at a constant speed. This control algorithm can avoid rotor stalling due to loss of steps. Experimental result shows that with the help of adaptive quick-start technique, the start time of the device can be shortened by up to 36.6%.

Superhydrophobic Drag-Reduction Spherical Bearing Fabricated by Laser Ablation and PEI Regulated ZnO Nanowire Growth

The resistance of the bearing is a significant factor affecting the performance of the ball-disk rotor gyroscope. The micro and nano combined surface with low surface energy material modifications can be hydrophobic. This can reduce the drag when the bearing is lubricated by deionized water. Laser ablation method is utilized to form micron-scaled structures on the surface of the stainless steel rotor ball. And the nanostructures are formed by PEI (Polyetherimide) regulated ZnO nanowires growth. After low surface energy material modification, the water contact angle of processed surface was 163° and the sliding angle was less than 4°. The maximum rotational speed was enhanced by up to 82.77% at 1.5 W driving power. Experiments show that the superhydrophobic drag-reduction spherical bearing has good short-term reliability. At 5 V drive voltage, the bearing can extend the rotational speed of ball-disk rotor gyroscope to 35000 rpm, and maintain the normal operation for longer than 40 minutes. This is quite meaningful for short-term-work or one-time-use rotor gyroscopes.

Hardware-in-the-loop attitude control via a high-order sliding mode controller/observer

In this study, a hardware-in-the-loop implementation of attitude control algorithms based on high-order sliding mode theory is performed and then both compared in terms of performance and functionality. The spacecraft simulator consists of a free-floating platform hinged on a spherical air-bearing support. In order to compensate for the unreliable performance of the rate gyros, a super-twisting sliding mode observer is incorporated to estimate the angular velocities fed back to the controller unit. The proposed scheme makes full use of novel sliding mode methods to alleviate the chattering effects without increasing the control effort; both controllers and observer are tuned to deal with the saturation of reaction wheels with respect to momentum and its rate. The ab initio simulations compared well with the simulator responses, implying that involved instruments including actuators and sensors have been properly emulated. This also proved that the external disturbances were modeled in a reliable manner. The robustness and effectiveness of the proposed scheme have been validated experimentally under extreme circumstances of disturbances and levels of uncertainties.

Investigations into the Integration of Low-Cost GPS/INS Sensors


 
 
 
 Global Positioning System (GPS) provides a method for directly obtaining instantaneous position and velocity estimates using satellites based passive range measurements. GPS is a whole day, all weather, passive, satellite-positioning system. Inertial Navigation System (INS) is a navigation aid system that uses a computer, Inertial Measurement Unite (IMU) that include motion sensors and rotation sensors to continuously calculate the position, orientation, and velocity relative to a known starting point. The integration of GPS/INS can help to overcome the limitations of the two systems providing integrated system better than either on a stand-alone basis. The integration of low-cost INS with dual frequency GPS has been widely studied and the same for the integration of tactical grid INS with low-cost GPS. However, during the last a few years, a number of low-cost GPS\low-cost INS integrated system have been introduced and become more and more common. For such integration level to be used in engineering applications, reliable investigations into the advantages and limitations are still needed and more efforts are required, which will be the focus of this paper.
 
 
 
 
 The methodology followed in this paper for evaluating the integration of low-cost GPS/INS sensors depends on evaluating the two sensors individually and comparing the results with those of the integrated system. The results show that low-cost single frequency GPS receivers are able to provide a comparable accuracy level in both static and kinematic carrier phase differential GPS(DGPS). As for low-cost Micro-Electro-Mechanical System (MEMS) based IMU, the accelerometers have provided instability comparing to gyros. The performance of gyros can be improved based on modelling the linear behaviour of the gyro drift. Tests show that such integration level degrades the precision of the gyro measurements and may not add any improvements to the quality of the individual GPS positioning.

Research on Time-series Modeling and Filtering Methods for MEMS Gyroscope Random Drift Error

The precision of MEMS gyroscope is reduced by random drift error. This paper applied time series analysis to model random drift error of MEMS gyroscope. Based on the model established, Kalman filter was employed to compensate for the error. To overcome the disadvantages of conventional Kalman filter, Sage-Husa adaptive filtering algorithm was utilized to improve the accuracy of filtering results and the orthogonal property of innovation in the process of filtering was utilized to deal with outliers. The results showed that, compared with conventional Kalman filter, the modified filter can not only enhance filter accuracy, but also resist to outliers and this assured the stability of filtering thus improving the performance of gyroscopes.

Z-Axis Micromachined Tuning Fork Gyroscope with Low Air Damping

This paper reports on the design and fabrication of a z-axis tuning fork gyroscope which has a freestanding architecture. In order to improve the performance of the tuning fork gyroscope by eliminating the influence of the squeeze-film air damping, the driving and sensing parts of the gyroscope were designed to oscillate in-plane. Furthermore, by removing the substrate underneath the device, the slide-film air damping in the gap between the proof masses and the substrate was eliminated. The proposed architecture was analyzed by the finite element method using ANSYS software. The simulated frequencies of the driving and sensing modes were 9.788 and 9.761 kHz, respectively. The gyroscope was fabricated using bulk micromachining technology. The quality factor and sensitivity of the gyroscope operating in atmospheric conditions were measured to be 111.2 and 11.56 mV/°/s, respectively.

High-accuracy absolute rotation rate measurements with a large ring laser gyro: establishing the scale factor.

Large ring lasers have exceeded the performance of navigational gyroscopes by several orders of magnitude and have become useful tools for geodesy. In order to apply them to tests in fundamental physics, remaining systematic errors have to be significantly reduced. We derive a modified expression for the Sagnac frequency of a square ring laser gyro under Earth rotation. The modifications include corrections for dispersion (of both the gain medium and the mirrors), for the Goos-Hänchen effect in the mirrors, and for refractive index of the gas filling the cavity. The corrections were measured and calculated for the 16 m2 Grossring laser located at the Geodetic Observatory Wettzell. The optical frequency and the free spectral range of this laser were measured, allowing unique determination of the longitudinal mode number, and measurement of the dispersion. Ultimately we find that the absolute scale factor of the gyroscope can be estimated to an accuracy of approximately 1 part in 108.

Hybrid fiber resonator employing LRSPP waveguide coupler for gyroscope

Polarization error and temperature noise are two main limits to the performance of resonant fiber optic gyroscope (RFOG). To overcome these limits, we demonstrated a hybrid resonator consisting of a polymer-based long-range surface plasmon polariton (LRSPP) waveguide coupler and a silica fiber. Single-polarization property of LRSPP waveguide and the offsetting of the opposite thermo-optical characteristics between the polymer-based LRSPP waveguide and the silica fiber can effectively inhibit both the polarization error and the temperature noise of RFOG. The measured resonance spectrum of the hybrid resonator shows the absence of polarization noise. The temperature dependence of wavelength shift (TDWS) of resonator dropped to about 2 pm/°C, or even to 0 pm/°C with optimal structure, which dramatically improves the temperature stability of gyroscope system. In addition, the hybrid resonator also shows tremendous application potential in rate-grade and tactical-grade gyroscopes.