Suppression of the G-sensitive drift of laser gyro in dual-axis rotational inertial navigation system

The dual-axis rotational inertial navigation system(INS)with dithered ring laser gyro(DRLG)is widely used in high precision navigation.The major inertial sensor errors such as drift errors of gyro and accelerometer can be averaged out,but the G-sensitive drifts of laser gyro cannot be averaged out by indexing.A 16-position rotational simulation experiment proves the G-sensitive drift will affect the long-term navigation error for the rotational INS quantitatively.The vibration coupling and asymmetric structure of the DRLG are the main errors.A new dithered mechanism and optimized DRLG is designed.The validity and efficiency of the optimized design are conformed by 1 g sinusoidal vibration experiments.An optimized inertial measurement unit(IMU)is formulated and measured experimentally.Laboratory and vehicle experimental results show that the divergence speed of longitude errors can be effectively slowed down in the optimized IMU.In long term independent navigation,the position accuracy of dual-axis rotational INS is improved close to 50%,and the G-sensitive drifts of laser gyro in the optimized IMU are less than 0.0002°/h.These results have important theoretical significance and practical value for improving the structural dynamic characteristics of DRLG INS,especially the highprecision inertial system.

Dynamic model and simulation of aseismatic system about laser gyro strapdown inertial measure assembly based on MSTMM

The precision of the laser gyro used in tactical missiles is poor because of dithering frequency,actuating by vibration,shock and overload in dynamical environment.This paper introduces the transfer matrix method of the multibody system（MSTMM）,establishes the dynamic model of the laser gyro strapdown inertial measure assembly aseismatic system,and analyzes the precision affected by dithering of the laser gyro and shocking of the tactical missile.And the dynamic response of the laser gyro strapdown inertial measure assembly aseismatic system is obtained by simulating the multibody system model.The simulation result indicates a theoretical idea to design the vibration isolation for the laser gyro strapdown inertial measure assembly.

Integrated Design and Accuracy Analysis of Star Sensor and Gyro on the Same Benchmark for Satellite Attitude Determination System

As an important sensor in the navigation systems,star sensors and the gyro play important roles in spacecraft attitude determination system.Complex environmental factors are the main sources of error in attitude determination.The error influence of different benchmarks and the disintegration mode between the star sensor and the gyro is analyzed in theory.The integrated design of the star sensor and the gyro on the same benchmark can effectively avoid the error influence and improves the spacecraft attitude determination accuracy.Simulation results indicate that when the stars sensor optical axis vectors overlap the reference coordinate axis of the gyro in the same benchmark,the attitude determination accuracy improves.

高精度惯性导航系统的技术预见

面对水下装备无人化/智能化的发展趋势,系统分析国内外知名惯性导航系统生产公司的产品,梳理水下装备的核心设备—惯性导航系统的发展趋势。基于工具检索国内外知名惯性导航系统公司的公开文献、专利以及产品手册等开源信息,提炼关键信息以及参数进行对比分析。目前,光纤陀螺惯性导航系统在国内已成为实现水下装备高精度定位的核心产品,基于谐振陀螺的惯性导航系统尚处于研发阶段。国际市场上,基于激光陀螺的惯性导航产品正逐渐被基于谐振陀螺和光纤陀螺的惯性产品替代。从法国赛峰和Exail这两家顶尖公司的产品指标看,谐振陀螺高精度惯性产品相比光纤陀螺高精度惯性产品而言,无论在体积还是在质量上都有较大优势,后续可能完全替代光纤陀螺系统成为市场主流。

Precision Balance Method for Cupped Wave Gyro Based on Cup-bottom Trimming

The mechanical balance process is the key process to eliminate the quadrature error and improve the performance of the cupped wave gyro. The conventional mechanical balance method for cupped wave gyro based on cup-wall trimming requires high control accuracy of trimming quantity, which increases the production cost and decreases the fabrication efficiency in large extent. However, it is hard to reach the high balance accuracy with the natural frequency split of mHz grade by using the conventional method. In this paper, the lumped mass dynamic model of the cupped wave gyro is built by discretization method, and the effects of different position trimming on the natural frequency are analyzed. It is pointed out that trimming off a tiny quantity of material from cup-wall causes large variation of the natural frequency is the main reason for the low accuracy of the conventional mechanical balance method. Then, a precision balance method for cupped wave gyro based on cup-bottom trimming is presented and the entire procedures of this method are given. The static balance process and dynamic balance process of the precision balance method are simulated by the finite element software. The simulation result shows that the precision balance method based on cup-bottom trimming brings less additional natural frequency split in the static balance process, minimizes the natural frequency split to mHz grade and rectify the angle of mode offset to 0.1° grade in the dynamic balance process, furthermore, the method decreases the requirement for control accuracy of trimming quantity evidently. The research work provides references for structure optimization design and balance process plan of the cupped wave gyro.

Research on fiber optic gyro signal de-noising based on wavelet packet soft-threshold

Gyro＇s drift is not only the main drift error which influences gyro＇s precision but also the primary factor that affects gyro＇s reliability. Reducing zero drift and random drift is a key problem to the output of a gyro signal. A three-layer de-nosing threshold algorithm is proposed based on the wavelet decomposition to dispose the signal which is collected from a running fiber optic gyro （FOG）. The coefficients are obtained from the three-layer wavelet packet decomposition. By setting the high frequency part which is greater than wavelet packet threshold as zero, then reconstructing the nodes which have been filtered out noise and interruption, the soft threshold function is constructed by the coefficients of the third nodes. Compared wavelet packet de-noise with forced de-noising method, the proposed method is more effective. Simulation results show that the random drift compensation is enhanced by 13.1%, and reduces zero drift by 0.052 6°/h.

Error analysis and a new steering law design for spacecraft control system using SGCMGs

Based on the singular value decomposition theory,this paper analyzed the mechanism of escaping/avoiding singularity using generalized and weighted singularity-robust steering laws for a spacecraft that uses single gimbal control moment gyros （SGCMGs） as the actuator for the attitude control system.The expression of output-torque error is given at the point of singularity,proving the incompatible relationship between the gimbal rate and the output-torque error.The method of establishing a balance between the gimbal rate and the output-torque error is discussed,and a new steering law is designed.Simulation results show that the proposed steering law can effectively drive SGCMGs to escape away from singularities.

Electrical crosstalk-coupling measurement and analysis for digital closed loop fibre optic gyro

The phase modulation and the closed-loop controller can generate electrical crosstalk-coupling in digital closed- loop fibre optic gyro. Four electrical cross-coupling paths are verified by the open-loop testing approach. It is found the variation of ramp amplitude will lead to the alternation of gyro bias. The amplitude and the phase parameters of the electrical crosstalk signal are measured by lock-in amplifier, and the variation of gyro bias is confirmed to be caused by the alternation of phase according to the amplitude of the ramp. A digital closed-loop fibre optic gyro electrical crosstalk-coupling model is built by approximating the electrical cross-coupling paths as a proportion and integration segment. The results of simulation and experiment show that the modulation signal electrical crosstalk-coupling can cause the dead zone of the gyro when a small angular velocity is inputted, and it could also lead to a periodic vibration of the bias error of the gyro when a large angular velocity is inputted.

Using genetic algorithm to learn neural network identifier for modeling gyro startup drift rate

Studies the modeling of gyro startup drift rate from acquired experimental gyro startup drift rate data and the nonlinear dynamic models of gyro startup drift rate related temperature established by time delay neural network which enables the gyro temperature drift rate to be compensated in the process of startup and the gyro instant startup to be implemented. And introduces an improved genetic algorithm to learn the weights of neural network identifier to avoid stacking into the local minimal value and achieve rapid convergence.

Research on feasibility of missile attitude control based on laser gyroscope

According to the disadvantages of traditional mechanical gyro inertial measurement unit('IMU') for steering system not being available for missile attitude control, a concept based on laser gyro IMU is proposed to realize navigation & positioning and attitude control. The concept will save three single-axis rate gyros compared with traditional missile attitude control system, and is available both for strapdown and platform inertial navigation systems. Firstly, this article analyzes the selection requirements of sensitive device for missile attitude control system, and then analyzes the feasibility of missile attitude control based on laser gyro theoretically, on this basis, from four aspects of error characteristics, anti-vibration characteristics, temperature characteristics and dynamic characteristics, validate the feasibility of the concept practically. Secondly according to the strict requirements of dynamic characteristics on attitude control system, a special design is made for gyro signal filtering used for attitude control. By changing the traditional high order FIR filter to adaptive filter and low order FIR filter, laser gyro's signal phase delay is reduced. The delay time of theoretical design is 1.5 ms. Lastly, this design is validated through an angle vibration test, and test curve indicates that the dynamic characteristics of laser gyro completely meets the requirements of the attitude control system, and the maximum delay time is 1.6144 ms, which satisfies with the attitude update rate of 2 ms per frame. This concept can simplify the missile guidance system design, at the same time, it does not reduce missile guidance accuracy, and also provides reference for the broadening of the application of laser gyro.

A novel adaptive finite-time controller for synchronizing chaotic gyros with nonlinear inputs

In this paper, the problem of the finite-time synchronization of two uncertain chaotic gyros is discussed. The parameters of both the master and the slave gyros are assumed to be unknown in advance. The effects of model uncertainties and input nonlinearities are also taken into account. An appropriate adaptation law is proposed to tackle the gyros＇ unknown parameters. Based on the adaptation law and the finite-time control technique, proper control laws are introduced to ensure that the trajectories of the slave gyro converge to the trajectories of the master gyro in a given finite time. Simulation results show the applicability and the efficiency of the proposed finite-time controller.

Underactuated spacecraft angular velocity stabilization and three-axis attitude stabilization using two single gimbal control moment gyros

Angular velocity stabilization control and attitude stabilization control for an underactuated spacecraft using only two single gimbal control moment gyros （SGCMGs） as actuators is investigated. First of all, the dynamic model of the underactuated spacecraft is established and the singularity of different configurations with the two SGCMGs is analyzed. Under the assumption that the gimbal axes of the two SGCMGs are installed in any direction, and that the total system angular momentum is not zero, a state feedback control law via Lyapunov method is designed to globally asymptotically stabilize the angular velocity of spacecraft. Under the assumption that the gimbal axes of the two SGCMGs are coaxially installed along anyone of the three principal axes of spacecraft inertia, and that the total system angular momentum is zero, a discontinuous state feedback control law is designed to stabilize three-axis attitude of spacecraft with respect to the inertial frame. Furthermore, the singularity escape of SGCMGs for the above two control problems is also studied. Simulation results demonstrate the validity of the control laws.

Chaos suppression of uncertain gyros in a given finite time

The gyro is one of the most interesting and everlasting nonlinear dynamical systems, which displays very rich and complex dynamics, such as sub-harmonic and chaotic behaviors. We study the chaos suppression of the chaotic gyros in a given finite time. Considering the effects of model uncertainties, external disturbances, and fully unknown parameters, we design a robust adaptive finite-time controller to suppress the chaotic vibration of the uncertain gyro as quickly as possible. Using the finite-time control technique, we give the exact value of the chaos suppression time. A mathematical theorem is presented to prove the finite-time stability of the proposed scheme. The numerical simulation shows the efficiency and usefulness of the proposed finite-time chaos suppression strategy.

IDENTIFICATION OF GYRO DRIFTS UNDER THREE AXIS ATTITUDE COUPLING

ＩＤＥＮＴＩＦＩＣＡＴＩＯＮＯＦＧＹＲＯＤＲＩＦＴＳＵＮＤＥＲＴＨＲＥＥＡＸＩＳＡＴＴＩＴＵＤＥＣＯＵＰＬＩＮＧＪＩＮＧＷｕｘｉｎｇ（荆武兴），ＷＡＮＧＸｕｅｘｉａｏ（王学孝），ＷＵＹａｏｈｕａ（吴瑶华）（ＨａｒｂｉｎＩｎｓｔｉｔｕｔｅｏｆＴｅｃｈｎ...

Sensitivity enhancement of micro-optical gyro with photonic crystal

We propose a core rotation-sensing element for improving the sensitivity of the micro-optical gyroscope using the large nonreciprocal effect with a photonic crystal.The sharp transmission peak of electromagnetically induced transparency in photonic crystal generated from a periodic distribution of cold atoms is sensitive to the rotation.Our numerical results show that the sensitivity of relative rotation is about 50 times higher and the sensitivity of absolute rotation is more than two orders higher than that of the traditional resonant optical gyroscope.Also,the sensitivity of the gyroscope can be manipulated by varying the atomic density,modulation frequency,probe pulse width,and photonic crystal length,etc.

Polarization properties in a prism laser gyro with mechanical dither bias

Theoretical analysis and experimental research on the polarization properties of output light in gyro are carried out to investigate the phenomenon that the amplitude of an output voltage signal is modulated by dither bias in laser gyros consisting of totally reflecting prisms. Taking the effect of prism stress birefringence into account, an analytical formula of the output light intensity in the gyro and the relationship between the polarization parameter and the amplitude modulation of the output signal are obtained and discussed. For the first time, the polarized power value of the output light is adopted as a basis to estimate the output signal amplitude fading extent of laser gyros. Experimental results demonstrate that when the value of polarized power of output light is below 25.5% of that in ideal static case, the standard error is over 0.0337 dBm, and the displacement extent of the prism is higher than 53% of the radius of the beam waist in the gyro cavity, the amplitude modulation extent of gyro output signal can reach up to 16%, which badly influences the measurement accuracy of the laser gyro. Using this polarized power detecting measurement method can repair the gyro immediately during its fabrication process, improve the testing and production efficiency and shorten the product development cycle.

gyro=急螺? thermo-mechanics=?

季文美先生(1912～2001)有次谈起,他曾想把陀螺仪表的词头gyro在汉文定名为“急螺”．这是个好主意,gyro=急螺,英汉音义均近．陀螺仪表起源于gyroscope,当年Foucault J．为演示转动(gyro,指地球的自转)而造的仪器(scope)．后来的航海和航海仪表,则主要利用仪表中陀螺转子高速转动．陀螺,在汉语里原指一种玩具,即英语中的top．

The research on signal-obtaining pattern for a new type of gyroscope

In this paper, a photoelectric signal obtained scheme via equator triangle pattern engraved on rotor is discussed and the mathematic model is deduced in the case which is deflexion between rotor axis and the coordinate frame of case. The deflexion error and coupling error under the situation are analyzed. Finally, three methods of engraving based on the spherical triangle pattern are presented. The error models of various methods are built up and the simulation curves are provided respectively. We have done the primary experiments on the surface of rotor using this method. It can be seen from the enlarged figures that the rim of the pattern is smooth and the demand of sensor resolution is satisfied by and large. The results of study supply reference for signal obtaining.

Application of Genetic Algorithm in Estimation of Gyro Drift Error Model

Extended Kalman Filter(EKF)algorithm is widely used in parameter estimation for nonlinear systems.The estimation precision is sensitively dependent on EKF’s initial state covariance matrix and state noise matrix.The grid optimization method is always used to find proper initial matrix for off-line estimation.However,the grid method has the draw back being time consuming hence,coarse grid followed by a fine grid method is adopted.To further improve efficiency without the loss of estimation accuracy,we propose a genetic algorithm for the coarse grid optimization in this paper.It is recognized that the crossover rate and mutation rate are the main influencing factors for the performance of the genetic algorithm,so sensitivity experiments for these two factors are carried out and a set of genetic algorithm parameters with good adaptability were selected by testing with several gyros’experimental data.Experimental results show that the proposed algorithm has higher efficiency and better estimation accuracy than the traversing grid algorithm.

Soft initial-rotation and H_∞ robust constant rotational speed control for rotational MEMS gyro

A novel soft initiai-rotation control system and an H∞ robust constant rotational speed controller （RCRSC） for a rotational MEMS （micro-electro-mechanical system） gyro are presented. The soft initial-rotation control system can prevent the possible tumbling down of the suspended rotor and ensure a smooth and fast initial-rotation process. After the initial-rotation process, in order to maintain the rotational speed accurately constant, the RCRSC is acquired through the mixed sensitivity design approach. Simulation results show that the actuation voltage disturbances from the internal carrier waves in the gyro is reduced by more than 15.3 dB, and the speed fluctuations due to typical external vibrations ranging from 10 Hz to 200 Hz can also be restricted to 10^-3 rad/s order.