High-precision Gyroscope Research Articles

Solution to the problem of detecting a malfunction of the position sensor of small spacecraft

The classic scheme for constructing a modern system for controlling the parameters of the angular motion of a spacecraft involves the use of high-precision gyroscopes, periodically adjusted according to the readings of optoelectronic devices. The most widely used in orientation and navigation systems are precision angular velocity sensors and gyroscopes on an electrostatic suspension, which determine the angles of rotation of the aircraft around its center of mass; Angular and linear accelerometers are also used, mounted in a certain way on the body of the aircraft.

Comprehensive analysis on the magnetic field error of a K–Rb–21Ne comagnetometer with low-frequency bias magnetic field sensitivity

The spin-exchange relaxation-free comagnetometer (SERFC) is of important research value compared to existing high-precision gyroscopes because of its extremely high theoretical limit sensitivity and long-term stability, in which one significant limiting factor is the magnetic field error. First, the relationship between the magnetic field gradient and the nuclear spin relaxation mechanism is introduced into the frequency response and steady-state response models of SERFC. Then, a novel method for suppression of the low-frequency magnetic field error based on the modified bias magnetic field sensitivity model is proposed. Finally, the effectiveness of the proposed suppression methods is demonstrated by optimizing the cell temperature, pump light power, and compensation magnetic field gradient to increase the suppression factor by 72.19%, 20.24%, and 69.86%, and the corresponding bias instability increased by 55.41%, 20.84%, and 27.63%, respectively. This study contributes to improving the long-term zero bias stability of the SERFC.

Compensation of scale factor nonlinear error introduced by harmonic distortion for open-loop fiber optic gyroscopes.

The scale factor (SF) of a gyroscope is the ratio of the detection output rotational rate and the input, and is expected to be a constant. However, for open-loop interferometric fiber optic gyroscopes (IFOGs) with sinusoidal modulation, harmonic amplitudes are inevitably affected by detection defects, such as nonuniform frequency response of the photodetector or unequal gain of amplification circuits. As a result, harmonic distortion leads to SF nonlinearity, which seriously hinders the accuracy of high-precision gyroscopes. In this Letter, the theoretical form of the SF error introduced by harmonic distortion of open-loop gyroscopes is analyzed, and an effective and simple compensation method is proposed. Instead of traversing the whole dynamic range, the proposed method simplifies the calibration pretest, where only a section of the dynamic range needs to be tested. Experimental results on an open-loop IFOG prototype show that, with our proposed method, the SF nonlinear error is suppressed to 2.5 ppm within the range -300 to +300∘/s, which is 33 times less than that before compensation.

Implementation of Effective Scale Factor Matching and Axial Centripetal Error Compensation for a Rotating Accelerometer Gravity Gradiometer

Rotating accelerometer gravity gradiometer (RAGG) is the only gravity gradient measuring device in the world to achieve commercial applications. When the parameter consistency among multiple accelerometers of the RAGG is not sufficient, its combined output cannot effectively suppress common-mode noise in the environment. A method for suppressing RAGG’s linear and angular motion noise is presented in this article by projecting the parameters, including scale factor, misalignment angle, second-order terms, and cross-coupling terms, onto the Cartesian coordinate system of the turntable plane. Proposing the algorithm implementation scheme of three effective scale factor solver loops, and for further canceling the motion residual error, high-precision gyroscope compensation loops are introduced. The added error compensation loop obtains the angular acceleration by differencing the angular velocity measured by the gyroscope, which in turn adjusts the loop parameters. Experimental results show that with the proposed method, the noise suppression of linear motion common-mode acceleration reaches 6.5 orders of magnitude, that is, the noise level <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.7 \times {10^{ - 8}} {\mathrm{ g/}}\sqrt {{\mathrm{Hz}}} $ </tex-math></inline-formula> of the accelerometer at the rotation frequency, and the angular motion common-mode acceleration noise is suppressed by six orders of magnitude, and the noise level <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.8 \times {10^{ - 8}} {\mathrm{ g/}}\sqrt {{\mathrm{Hz}}} $ </tex-math></inline-formula> of the accelerometer at the swing frequency is also obtained.

Comprehensive analysis on the dynamic characteristic of K-Rb-21Ne co-magnetometer with transient response

Spin-exchange relaxation-free (SERF) co-magnetometer is expected to be a high-precision gyroscope, but the slow response speed severely restricts its practicality. In this paper, a transient response analysis is proposed to give comprehensively quantify the dynamic characteristic of the SERF co-magnetometer. A compensation magnetic field configuration is proposed for the fastest response speed the system can achieve. The results show that the system gets the fastest response speed at the dynamic compensation point we proposed and the response speed of the system at that point is 19.36 times faster than that at the traditional magnetic compensation point. In addition, derived from experimental data, the spin-exchange relaxation induced by magnetic fields is observed and quantified, which decreases the sensitivity of inertia and magnetic measurement. This research supports improving the response speed of SERF co-magnetometer and expanding its application range, such as platform inertial navigation systems.

Aerodynamic characteristics analysis of a multiscale hemispherical dynamic pressure motor based on similarity theory

Hemispherical dynamic pressure motors (HDPMs) are used in high precision gyroscope instruments, and the aerodynamic characteristics of gas in bearing clearance have an important influence on gyroscope accuracy. Due to the multiscale structure of the gas domain, there are few valuable studies on the aerodynamic characteristics of the HDPM. In this paper, a calculation model of HDPM was established based on similarity theory and computational fluid dynamics (CFD) method, which was solved under different conditions. The results indicate that the load force and resistance torque of the gas film are inversely proportional to the clearance size between the stator and rotor, which are also significantly related to the gas viscosity and the type of pressure outlet. This work can provide a method for the investigation of dynamic pressure characteristics for the multiscale fluid, and can also provide a reference for the optimal design and fault diagnosis of dynamic pressure motors.

An Efficient Calibration Method for Triaxial Gyroscope

This paper presents an efficient servomotor-aided calibration method for the triaxial gyroscope. The entire calibration process only requires approximately one minute, and does not require high-precision equipment. This method is based on the idea that the measurement of the gyroscope should be equal to the rotation speed of the servomotor. A six-observation experimental design is proposed to minimize the maximum variance of the estimated scale factors and biases. In addition, a fast converging recursive linear least square estimation method is presented to reduce computational complexity. The simulation results reflect the robustness of the calibration method under normal and extreme conditions. We experimentally demonstrate the feasibility of the proposed method on a robot arm, and implement the method on a microcontroller. We verify the calibration results of the proposed method by comparing with a traditional turntable approach, and the experiment indicates that the results of these two methods are comparable. By comparing the calibrated low-cost gyroscope reading with the reading from a high-precision gyroscope, we can conclude that our method significantly increases the gyroscope’s accuracy.

A method to improve tracking ability of drive control of MEMS gyroscopes

PurposeA high-precision gyroscope is an important tool for accurate positioning, and the amplitude stability and frequency tracking ability of the drive control system are important and necessary conditions to ensure the precision of micro-electro-mechanical systems (MEMS) gyroscopes. To improve the precision of MEMS gyroscopes, this paper proposes a method to improve the amplitude stability and frequency tracking ability of a drive control system.Design/methodology/approachA frequency tracking loop and an amplitude control loop are proposed to improve the frequency tracking ability and amplitude stability of the drive control system for a MEMS gyroscopes. The frequency tracking loop mainly includes a phase detector, a frequency detector and a loop filter. And, the amplitude control loop mainly includes an amplitude detector, a low-pass filter and an amplitude control module. The simulation studies on the frequency tracking loop, amplitude control loop and drive control system composed of these two loops are implemented. The corresponding digital drive control algorithm is realized by the Verilog hardware description language, which is downloaded to the application-specific integrated circuits (ASIC) platform to verify the performances of the proposed method.FindingsThe simulation experiments in Matlab/Simulink and tests on the ASIC platform verify that the designed drive control system can keep the amplitude stable and track the driving frequency in real time with high precision.Originality/valueThis study shows a way to design and realize a drive control system for MEMS gyroscopes to improve their tracking ability. It is helpful for improving the precision of MEMS gyroscopes.

A digital output MEMS DRG on-chip temperature compensation method based on virtual sensor

A digital output Disk Resonator Gyroscope (DRG) on-chip temperature compensation method based on virtual sensor is proposed in this paper. DRG is a combination of solid wave gyroscope and MEMS gyroscope, it has become the research emphasis of high precision gyroscope. In practical application, the ambient temperature changing will cause several problems such as the change of scale factor, zero drift and so on. To increase the environmental adaptability of DRG, the DRG temperature characteristics are analyzed, the temperature compensation models of scale factor and zero output are established in this paper. The concept of virtual temperature sensor is introduced to solve the lead or lag problem caused by integrated temperature sensor. Based on the trend of AC drive amplitude changing with temperature, the temperature measurement is converted into AC voltage amplitude measurement. The virtual temperature sensor is used to complete the on-chip temperature compensation of the DRG angular velocity output, the second-order compensation realizes the scale factor change of 40 ppm/[Formula: see text]C and zero output change of 27[Formula: see text]/h over the full temperature range varying from [Formula: see text] to 60[Formula: see text]C according to the simulation result.

Reanalyzing Atomic Beam Interferometric Gyroscopes: Dependence of Sensitivity on Experimental Parameters

As an important technique for developing high-precision gyroscopes, atom interferometry with continuous atomic beams has exhibited advantages of high short-term sensitivity and dynamic response relative to that with periodically launched atom clouds. This article reanalyzes the characteristics of an atomic beam interferometric gyroscope from perspectives including the continuous operation mode and the modified sensitivity dependence on laser and atomic sources. Specific requirements on certain experimental parameters are explored including the Raman beam diameter, detection beam diameter, atomic flux, laser power, laser phase noise, atomic longitudinal and transverse velocity distributions. The parameter determining strategy is discussed to achieve target sensitivity with controlled conditions such as system volume and operating bandwidth. The results would provide strong support on analytical method and data reference for further improvement of atomic beam interferometric gyroscopes.

Optimal design of a high homogeneous and small-size shim coil for atomic spin gyroscope based on 0-1 linear programming

It is necessary to develop a high homogeneous, low power consumption, high frequency and small-size shim coil for high precision and low-cost atomic spin gyroscope (ASG). To provide the shim coil, a multi-objective optimization design method is proposed. All structural parameters including the wire diameter are optimized. In addition to the homogeneity, the size of optimized coil, especially the axial position and winding number, is restricted to develop the small-size shim coil with low power consumption. The 0-1 linear programming is adopted in the optimal model to conveniently describe winding distributions. The branch and bound algorithm is used to solve this model. Theoretical optimization results show that the homogeneity of the optimized shim coil is several orders of magnitudes better than the same-size solenoid. A simulation experiment is also conducted. Experimental results show that optimization results are verified, and power consumption of the optimized coil is about half of the solenoid when providing the same uniform magnetic field. This indicates that the proposed optimal method is feasible to develop shim coil for ASG.

小型化高精度光纤陀螺的检测电路串扰自检测

小型化高精度光纤陀螺的检测电路串扰自检测

A Fast and Efficient Measurement System for Nuclear Spin Relaxation Times in Atomic Vapors.

With the rapid progress of cutting-edge research such as quantum measurement technology, nuclear magnetic resonance (NMR) gyroscopes represent a major development direction of high-precision micro-miniature gyroscopes, which have significant advantages such as high precision, small size, and low power consumption. It is meaningful to measure the relaxation times of noble-gas atoms which are crucial indicators to accurately and quickly characterize the vapor cell performance as a core component of gyroscopes. In this paper, a test platform for relaxation time is built and an automatic relaxation time test system based on free induction decay (FID) and the π pulse method is designed to accelerate the relaxation time test. Firstly, the formula of the atomic dynamic process based on the Bloch equation was deduced, a GUI (Graphical User Interface) simulation based on the derived differential equation was conducted, and the moving process of the magnetic moment was visually described. Then, the virtual instrument was used to integrate multiple test instruments into an auto-test system, and LabVIEW programming was used for control to realize the automation of the test process on the test platform. Finally, the test results in different conditions were compared. The results show that the test system is stable and reliable with excellent man–machine interaction, and the measurement efficiency was increased by about 185%, providing an effective test scheme for vapor cell performance.

Analysis of Kerr Noise in Angular-Rate Sensing Based on Mode Splitting in a Whispering-Gallery-Mode Microresonator.

Whispering-gallery-mode (WGM) microresonators have shown their potential in high-precision gyroscopes because of their small volume and high-quality factors. However, Kerr noise can always be the limit of accuracy. Angular-rate sensing based on mode splitting treats backscattering as a measured signal, which can induce mode splitting, while it is considered as a main source of noise in conventional resonator optical gyroscopes. Meanwhile, mode splitting also provides superior noise suppression owing to its self-reference scheme. Kerr noise in this scheme has not been defined and solved yet. Here, the mechanism of the Kerr noise in the measurement is analyzed and the mathematical expressions are derived, indicating the relationship between the Kerr noise and the output of the system. The influence caused by Kerr noise on the output is simulated and discussed. Simulations show that the deviation of the splitting caused by Kerr noise is 1.913 × 10−5 Hz at an angular rate of 5 × 106 °/s and the corresponding deviation of the angular rate is 9.26 × 10−9 °/s. It has been proven that angular-rate sensing based on mode splitting offers good suppression of Kerr noise.

Assembly Technology of Structure Stability Control for High Precision Gyroscope

Assembly Technology of Structure Stability Control for High Precision Gyroscope

A Novel MEMS Gyro North Finder Design Based on the Rotation Modulation Technique.

Gyro north finders have been widely used in maneuvering weapon orientation, oil drilling and other areas. This paper proposes a novel Micro-Electro-Mechanical System (MEMS) gyroscope north finder based on the rotation modulation (RM) technique. Two rotation modulation modes (static and dynamic modulation) are applied. Compared to the traditional gyro north finders, only one single MEMS gyroscope and one MEMS accelerometer are needed, reducing the total cost since high-precision gyroscopes and accelerometers are the most expensive components in gyro north finders. To reduce the volume and enhance the reliability, wireless power and wireless data transmission technique are introduced into the rotation modulation system for the first time. To enhance the system robustness, the robust least square method (RLSM) and robust Kalman filter (RKF) are applied in the static and dynamic north finding methods, respectively. Experimental characterization resulted in a static accuracy of 0.66° and a dynamic repeatability accuracy of 1°, respectively, confirming the excellent potential of the novel north finding system. The proposed single gyro and single accelerometer north finding scheme is universal, and can be an important reference to both scientific research and industrial applications.

Quantum-enhanced gyroscopy with rotating anisotropic Bose–Einstein condensates

High-precision gyroscopes are a key component of inertial navigation systems. By considering matter wave gyroscopes that make use of entanglement it should be possible to gain some advantages in terms of sensitivity, size, and resources used over unentangled optical systems. In this paper we consider the details of such a quantum-enhanced atom interferometry scheme based on atoms trapped in a carefully-chosen rotating trap. We consider all the steps: entanglement generation, phase imprinting, and read-out of the signal and show that quantum enhancement should be possible in principle. While the improvement in performance over equivalent unentangled schemes is small, our feasibility study opens the door to further developments and improvements.

가속도 및 각속도 데이터 융합 기반 유한요소모델 개선

유한요소모델 개선은 구조물의 설계검증, 손상추적, 내하력 평가 등 다양하게 활용되고 있는 기법이다. 일반적인 유한요소모델 개선은 구조물에서 계측된 가속도응답으로부터 구조물의 고유진동수와 모드형상을 구하고, 이를 바탕으로 모델을 개선하게 된다. 이와 같은 가속도응답기반 유한요소모델 개선은 구조물의 병진 자유도를 고려하기 때문에 물리적인 체계를 추정하는데 있어서 매우 적합하지만, 회전 자유도 상에서 변화하는 구조물의 경계조건을 판별하기에는 어려움이 있다. 최근 센서 기술의 개발로 인하여 저렴한 가격, 높은 정확성의 자이로센서들이 개발되고 있으며, 그에 따라 구조물의 회전 자유도에 관한 정보 획득이 용이해지고 있다. 본 연구에서는 이를 바탕으로 가속도와 각속도 응답을 함께 이용하는 데이터 융합 기반 유한요소모델 개선 기법을 제안하였다. 가속도와 각속도를 모두 활용한 데이터융합기법은, 가속도만 사용한 기존의 유한요소 모델 기법보다 구조물의 경계조건 판별에 정확한 정보를 제공한다. 본 논문에서는 단순보 모델을 이용한 수치 시뮬레이션을 통해서, 제안한 가속도와 각속도 데이터 융합기반의 유한요소모델 개선 기법의 성능을 검증하였다. The finite element (FE) model updating is a commonly used approach in civil engineering, enabling damage detection, design verification, and load capacity identification. In the FE model updating, acceleration responses are generally employed to determine modal properties of a structure, which are subsequently used to update the initial FE model. While the acceleration-based model updating has been successful in finding better approximations of the physical systems including material and sectional properties, the boundary conditions have been considered yet to be difficult to accurately estimate as the acceleration responses only correspond to translational degree-of-freedoms (DOF). Recent advancement in the sensor technology has enabled low-cost, high-precision gyroscopes that can be adopted in the FE model updating to provide angular information of a structure. This study proposes a FE model updating strategy based on data fusion of acceleration and angular velocity. The usage of both acceleration and angular velocity gives richer information than the sole use of acceleration, allowing the enhanced performance particularly in determining the boundary conditions. A numerical simulation on a simply supported beam is presented to demonstrate the proposed FE model updating approach.

Error Compensation Technology of Semi-Strapdown MEMS Inertial Measurement System

Semi-strapdown inertial measurement method provides a new solution for the high-precision measurement on flight attitude of high-spinning ammunition, while the specific set of components in the semi-strapdown application will cause a series of errors. This paper mainly analyzes the generation mechanism of motor speed fluctuation error and the misalignment error in coupling axis. Then the instantaneous motor speed measurement method based on the high-precision gyroscope is designed and the misalign model of coupling axis is set up, MEMS inertial measurement area centripetal force equation under the condition of high speed is worked out, and accuracy error parameters affecting the measurement are obtained. Finally, the paper provides corresponding error compensation method and comparative tests are conducted. The results show that the compensated system improves the accuracy of attitude angle calculating and the error has been effectively suppressed.

Advances in Atomic Gyroscopes: A View from Inertial Navigation Applications

With the rapid development of modern physics, atomic gyroscopes have been demonstrated in recent years. There are two types of atomic gyroscope. The Atomic Interferometer Gyroscope (AIG), which utilizes the atomic interferometer to sense rotation, is an ultra-high precision gyroscope; and the Atomic Spin Gyroscope (ASG), which utilizes atomic spin to sense rotation, features high precision, compact size and the possibility to make a chip-scale one. Recent developments in the atomic gyroscope field have created new ways to obtain high precision gyroscopes which were previously unavailable with mechanical or optical gyroscopes, but there are still lots of problems that need to be overcome to meet the requirements of inertial navigation systems. This paper reviews the basic principles of AIG and ASG, introduces the recent progress in this area, focusing on discussing their technical difficulties for inertial navigation applications, and suggests methods for developing high performance atomic gyroscopes in the near future.