随钻陀螺GyroSphere在渤海油田浅层防碰作业中的应用

随着渤海油田勘探开发的不断深入,平台槽口数量的不断增多,布井密度急剧增加,再加上隔水管及直井段偏斜的影响,大大增加了浅层碰撞套管的风险,防碰形势日益严峻。针对渤海油田某井浅层面临的突出防碰问题,首次引入斯伦贝谢随钻陀螺GyroSphere工具,安全顺利地完成了本井浅层防碰绕障作业。通过对本次施工的作业总结和技术展望,提出了利用随钻陀螺工具更好地解决相关问题的良好做法。

Target Seeker Gyro and Controls

A composite target seeker gyro with dual spectral range infrared rays and millimeter waves, and the associated control methodology are developed. The static pressure air floated ball bearing is used to sustain the outer frame, the optical fiber and wave guide are used to transmit these two kinds of signals to the rear part of the gyro, and the stator coils are used to get non contact angular measurement. Composite guiding, scanning, tracing and controlling can be achieved, the maximum tracing angular velocity can be as high as 16(°)/s.

Application of wavelet package filtering in the de-noising of fiber optic gyroscopes

To reduce the drift error existing in the output signal of fiber optic gyroscopes （FOG）, a mathematical model of the FOG output signal is set up; the error characteristics of the FOG output signal are analyzed, and semi-soft threshold filtering is chosen based on the comparison of hard threshold and soft threshold filtering. The semi-soft threshold wavelet package filtering method is applied in the filtering of the FOG output signal. Experiments of the stationary and dynamic FOG output signals filtered with the wavelet package analysis are carried out in a lab environment, respectively. Experiments done with the real-time measured FOG signal show that the method of semi-soft threshold wavelet package filtering reduces the mean square error from 5 （°）/h to 1 （°）/h, so it is effective in eliminating the white noises and the fractal noises existing in the FOG. The novel method proposed here is proved valid in reducing the FOG drift error, satisfying the technical demands of high precision and realtime processing.

GYRO BIAS ON-ORBIT CALIBRATION FOR MICRO SATELLITES

According to gyro application in micro-satellites, a new gyro bias real-time on-orbit calibration technology is presented and it is independent of any other sensors. The approach relies on gyro on-orbit measurements restricted by satellite attitude dynamics and estimates the gyro bias generated when the gyro is electrified. Observability of the calibration model is analyzed and applicable conditions of the technology are derived. Simulation results indicate that the calibration algorithm is accurate and robust at gyro sampling rate, and its convergence speed is fast. Within the given attitude dynamics model error, the convergence time is less than 100 s and the convergence accuracy is about 1.0 （°）/h. Calibration performance can meet requirements of spacecraft operations.

An Open-Loop Test of a Resonator Fiber Optic Gyro

The resonator fiber optic gyro （R-FOG） ,which utilizes a resonance frequency change due to the Sagnac effect,is a promising candidate for the next generation inertial rotation sensor. In this study, an open-loop R-FOG is set up using phase modulation spectroscopy. First,the demodulation curve is obtained using a lock-in amplifier. From the demodulation signal,a gyro dynamic range of ± 4.2rad/s is obtained. Then,using different phase modulation frequencies,the open-loop gyro output signal is measured when the gyro is rotated clockwise or counterclockwise. The bias drift as a function of time is also measured. The fluctuation of the output over 5s is about 0.02rad/s. The drift can be reduced by taking countermeasures against system noise.

Lumped parameter analytic modeling and behavioral simulation of a 3-DOF MEMS gyro-accelerometer

A new analytical model of a 3-degree-of-freedom （3-DOF） gyro-accelerometer system consisting of a 1-DOF drive and 2-DOF sense modes is presented. The model constructs lumped differential equations associated with each DOFof the system by vector analysis. The coupled differential equations thus established are solved analytically for their responses in both the time and frequency domains. Considering these frequency response equations, novel device design concepts are derived by forcing the sense phase to zero, which leads to a certain relationship between the structural frequencies, thereby causing minimization of the damping effect on the performance of the system. Furthermore, the feasibility of the present gyro-accelerometer structure is studied using a unique discriminatory scheme for the detection of both gyro action and linear acceleration at their events. This scheme combines the formulated settled transient solution of the gyro-accelerometer with the processes of synchronous demodulation and filtration, which leads to the in-phase and quadrature components of the system＇s output signal. These two components can be utilized in the detection of angular motion and linear acceleration. The obtained analytical results are validated by simulation in a MATLAB/Simulink environment, and it is found that the results are in excellent agreement with each other.

Analysis of deformation of rotor and influence on the performance of Gyro based on B-Spline wavelet FEM

Some construct characteristics and composing material of the new Gyro＇ s rotor are introduced. Some factors resulting in deformation of the rotor surface are analyzed. Under different loads such as the fo,＇ce of deflecting center, the change of temperature, the fo,ce of pressure and couple factors, the deformation of rotor is analyzed with the wavelet finite element simulation software. The vector distributing map of rotor reformation is given. The deformation resulting from the pressure force of photon is studied. Finally, the influence on Gyro＇ s performance because of anomalous surface of rotor due to deformation of rotor is researched and the result is useful to forecast the performance of the drift of gyroscope. The disturbing moment resulting from the deformation of rotor can be compensated using the mathematic method, and provides an important reference for both design and optimization of the rotor.

Error Analysis of a Dynamically Tuned Gyro Strapdown Northfinder

Aim To analyze the mathematical error model of a dynamically tuned gyro (DTG) strapdown northfinder in detail, guide the process of design, manufacture and adjustment of northfinder. Methods Each error source of this type of northfinder was determined, and the influence of each source on northfinding result was formulated. Results and Conclusion Under the guidance of the analysis, select relevant method for each source which has different effect on result to reduce northfinding error, a type of northfinder meeting the practical requirements of user was developed.

Implementation of field-aligned coordinates in a semi-Lagrangian gyrokinetic code for tokamak turbulence simulation

Field-aligned coordinates have been implemented in the gyrokinetic semi-Lagrangian code NLT, Ye et al （2016 J. Comput. Phys. 316 180）, to improve the computational efficiency for the numerical simulations of tokamak turbulence and transport. 4D B-spline interpolation in field- aligned coordinates is applied to solve the gyrokinetic Vlasov equation. A fast iterative algorithm is proposed for efficiently solving the quasi-neutrality equation. A pseudo transform method is used for the numerical integration of the gyro-average operator for perturbations with a high toroidal mode number. The new method is shown to result in an improved code performance for reaching a given accuracy. Some numerical tests are presented to illustrate the new methods.

GYROMAT 2000陀螺经纬仪定向程序探讨

本文对Gyromat 2000高精度自动陀螺经纬仪的定向程序进行了初步的探讨。首先介绍了自动陀螺仪定向的关键技术,如三点法和积分法观测原理,图解了步进测量的原理,这是分析定向程序的理论基础。接着对三个定向程序相关步骤的用时和精度进行了实测,并以测试结果为参照,对各定向程序进行了合理的猜测。本文的成果将对国产陀螺经纬仪的自动化进程起到一定的参考作用。

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.

Geometric Analysis of Singularity for Single-Gimbal Control Moment Gyro Systems

This research is focused on the singularity analysis for single-gimbal control moment gyros systems （SCMGs） which include two types, with constant speed （CSCMG） or variable speed （VSCMG） rotors. Through angular momentum hypersurfaces of singular states, the passable and impassable singular points are discriminated easily, meanwhile the information about how much the angular momentum workspace as well as the steering capability available is provided directly. It is obvious that the null motions of steering laws are more effective for the five pyramid configuration（FPC） than for the pyramid configuration（PC） from the singular plots. The possible degenerate hyperbolic singular points of the preceding configurations are calculated and the distinctness of them is denoted by the Gaussian curvature. Furthermore, failure problems to steer integrated power and attitude control system （IPACS） are also analyzed. A sufficient condition of choosing configurations of VSCMGs to guarantee the IPACS steering is given. The angular momentum envelops of VSCMGs, in a given energy and a limited range of rotor speeds, are plotted. The connection and distinctness between CSCMGs and VSCMGs are obtained from the point of view of envelops.

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.

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.

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.

Analysis of Error for a Rotating Strap-down Inertial Navigation System with Fibro Gyro

The error equation of a rotating inertial navigation system was introduced. The effect of the system's main error source (constant drift of gyro and zero bias of accelerometer) under rotating conditions for the system was analyzed. Validity of theoretical analysis was shown via simulation, and that provides a theoretical foundation for a rotating strap-down inertial navigation system during actual experimentation and application.

Research on identifying the dynamic error model of strapdown gyro on 3-axis turntable

The dynamic errors of gyros are the important error sources of a strapdown inertial navigation system. In order to identify the dynamic error model coefficients accurately, the static error model coefficients which lay a foundation for compensating while identifying the dynamic error model are identified in the gravity acceleration fields by using angular position function of the three-axis turntable. The angular acceleration and angular velocity are excited on the input, output and spin axis of the gyros when the outer axis and the middle axis of a three-axis turntable are in the uniform angular velocity state simultaneously, while the inner axis of the turntable is in different static angular positions. 8 groups of data are sampled when the inner axis is in 8 different angular positions. These data are the function of the middle axis positions and the inner axis positions. For these data, harmonic analysis method is applied two times versus the middle axis positions and inner axis positions respectively so that the dynamic error model coefficients are finally identified through the least square method. In the meantime the optimal angular velocity of the outer axis and the middle axis are selected by computing the determination value of the information matrix.

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.

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.

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.