High-Reliability Strapdown Platforms Using Two-Degree-of-Freedom Gyros

This paper presents a new concept of high-reliability strapdown attitude sensing systems for space vehicles. Each system utilizes a set of redundant two-degree-of-freedom gyros. An optimum system configuration is obtained for maximum system reliability and the best measurement accuracy. Improved accuracy of the final data is obtained by using the least-square data reduction technique. Each system possesses a ?sensor performance management? feature which is capable of failure detection, faulty gyro identification, system reconfiguration, and, possibly, sensor recalibration. Improvement in reliability, as compared to other types of strapdown systems, is demonstrated. Details of the development are described in terms of a system containing four gyros.     

Gyro Misalignment and Encoder Quantization Effects During Multi-Axis Evaluation of Strapdown Gyros

This paper presents a quantitative discussion of two error sources which affect the accuracy of data comparison between instrument outputs and reference angle computations during multi-axis evaluation of strapdown gyros. The error due to misalignment of gyro input axes is formulated in terms of closed-form solutions for typical relationships between the three table gimbal rotation histories. If the angular positions of the table gimbal axes are measured by shaft encoders, then any measurement has an uncertainty in the range from plus to minus one-half of the quantization level. It is shown that the effect of encoder quantization error on the computer transformed angles in the bodyfixed coordinate system can be divided into two parts: the initial uncertainty of the zero positions of the gimbals before table motion is begun, and all subsequent error contributions during table test. Typical data for gyro misalignment and encoder quantization error effects are presented.     

Comment on "Gyro Misalignment and Encoder Quantization Effects During Multi-Axis Evaluation of Strapdown Gyros"

A recent paper1 discusses certain aspects of strapdown attitude error sources. It is pointed out here that the long term effects of these and several additional sources have previously been determined, within the framework of a complete attitude reference [4] and navigation [5] system.     

Angular Velocity Measurement Using Rate Gyros in a Spinning Vehicle

It is shown that when the gyro spin vector is in opposition to the spin vector of the vehicle, the output differential equation of the gyro becomes unstable for large vehicle spin values. When the gyro is used with its spin vector along the spin vector of the vehicle, the steady-state response of the gyro is a nonlinear function of the roll rate of the vehicle.     

一种适用于捷联探测器的空间目标搜索算法

针对空间目标的搜索问题,提出了一种适用于捷联探测器的目标搜索算法。无论探测器是否能够获取目标方位的先验信息,该算法都能够使得搜索轨迹覆盖探测球面,确保目标的成功捕获。该算法分析了目标与探测器间相对运动以及姿态控制精度等因素对搜索轨迹的影响,给出了螺旋搜索轨迹重叠区域与相对运动角速度、姿态控制精度间的约束关系。对于算法生成的目标搜索轨迹,采用单轴定向姿态控制的方式给出了探测球面上搜索轨迹与姿态控制误差信号间的转换方法。最后通过典型情况下的仿真算例对算法进行了验证,仿真结果表明,无论是否具备目标方位先验信息,该算法都能够有效发现目标。     

Strapdown Guidance Error Analysis

A crucial part of so-called ?strapdown? techniques for inertial guidance systems is the generation of the matrix of direction cosines relating the body axes to the reference axes. This is generally done by direct integration of a set of differential equations having the body angular velocities as inputs. This paper is devoted to an error analysis of two commonly used integration schemes, namely, direction cosines and quaternions. Scale, skew, and drift errors are defined, and the susceptibility of the integration schemes to these types of error is examined. It is concluded that the quaternion scheme offers an advantage because it intrinsically yields zero skew error. The paper is presented in two parts, for convenience.     

捷联惯性测量组合标定方案

本文介绍了惯性组合标定“6位置12点采样”的编排方案,可补偿测试设备调平、对北误差的影响,测试过程简单合理。此外介绍了对组合性能有特殊意义的ωｅ、ｇ自检及迭代求解方法,并以此作为求算标准偏差的依据。     

光纤陀螺尖峰脉冲研究

对光纤陀螺尖峰脉冲进行了深入研究,建立了光纤陀螺前放电路的噪声模型,分析了两个关键参数带宽和放大倍数对陀螺噪声和信噪比的影响,仿真结果指出降低前放带宽、提高放大倍数可以大幅度提高陀螺的信噪比,由于光纤陀螺信号特性的限制,这些改变必须在切除尖峰脉冲后才可以实现。对比分析了常见的几种光纤陀螺尖峰脉冲抑制方案,选择了模拟开关切除尖峰脉冲方案进行试验,试验结果表明,尖峰脉冲抑制方案对光纤陀螺的输出数据噪声性能提升效果显著,改进后的陀螺噪声降低了13%。     

Analysis Strapdown Navigation Using Quaternions

A brief review of the theory of strapdown inertial navigation is presented in which the attitude of the sensor box with respect to inertial space is represented by the four-parameter quaternion vector. . A 4X4 matrix R is defined which aids in relating quaternions to direction cosines and facilitates interpretation of the equations for error propagation, which are also derived. In the interpretation, it is shown that the error in the quaternion vector causes aor-(correctable) scale factor error and an equivalent tilt vector error that propagates the same way as the platform tilt vector in a gimbaled system.     

半球谐振陀螺的基础理论研究

针对半球谐振陀螺的几个基本理论问题,对包括环形谐振子和半球谐振子的动力学理论、控制理论和信号处理理论等进行了系统的阐述和总结,建立了包括谐振子振动频率和进动特性、激励系统稳定性、信号处理等在内的半球谐振陀螺的基本理论框架,以期为今后的具体工程提供理论指导。     

单框架控制力矩陀螺奇异问题研究

 研究单框架控制力矩陀螺群的奇异问题。给出了一种新的奇异度量,并推导出利用该度量的简洁的零运动公式。对于不同的构型,该度量反映了陀螺群Jacobian矩阵求逆运算的误差灵敏度,且具有相同的取值范围,因此在分析各种构型的优劣时具有可比性。上述结论通过数值仿真给出了验证。对常用的行列式形式奇异度量,给出其零运动的清晰公式。基于奇异值分解,给出陀螺群的各类操纵律,证明了奇异方向与分解矩阵的关系,明确框架锁死出现的条件和鲁棒操纵律调控的依据。给出五棱锥构型奇异角动量体的切片图,为角动量体内奇异的出现提供了认识的方法;对失效情况下的五棱锥构型,通过奇异角动量曲面图和具体的切片图,直观地得到其内部形式和特性的显著变化。     

Navigation Computation in Terrestrial Strapdown Inertial Navigation Systems

The problem of computing the translational velocity and position relative to earth, which has to be solved by the processor of a strapdown inertial navigation system is discussed. Several approaches are briefly examined with consideration given to the form in which the sensor data are generated and to the computational burden involved in each approach. A computational scheme is finally selected in which the computation is divided into three rate levels. The differential equations of this scheme are developed and the assumptions on which the development is founded are stated. Three variants of the basic scheme are presented, each based on a different level of simplifying assumptions. The main purpose of this work is to develop the differential equations to be solved at each stage of the computation, rather than the numerical implementation of the solution. This work supplies the theoretical background for some of the numerical methods which are now being used.     

双框架控制力矩陀螺群的建模与分析

 研究采用双框架控制力矩陀螺群在卫星高精度姿态控制中的建模问题。对于中心刚体带有多个双框架控制力矩陀螺,构造了该系统的拉格朗日函数。采用拟拉格朗日方程建立了卫星姿态动力学模型。在建模中,陀螺的内、外框架未进行无惯量的假设,使得双框架运动带来的动力学特性得到了准确的反映;设计了适宜的标记,使得方程形式简洁并且统一。该模型为高精度的数学仿真和分析提供了基础。基于系统的拉格朗日函数,应用拉格朗日方程,分别建立了沿内、外框架轴和转子轴的轴向动力学方程,为执行机构伺服系统的动力学特性分析和控制器设计提供模型的依据。     

减小双轴旋转惯导中陀螺仪随机漂移影响的方法研究

针对双轴旋转惯导惯性器件的随机误差无法在导航过程中自动进行补偿的问题,提出优化的两位置重调(TPR)的方法来补偿系统的随机误差导致的方位和位置误差,以提高双轴旋转惯导的长航时精度.与传统两位置重调(CPR)方法相比,使用优化的误差传递方程的两位置重调的方法,可以在少于6h条件下估计出系统的方位误差,从而使得系统的位置精度和方位精度都得以极大的提高.根据惯性器件的随机误差导致的方位误差的特性,建立了TPR的误差模型.通过仿真,证明了该方法的有效性.     

捷联式重力测量技术研究进展

本文简要论述了动态重力测量的发展动态,接着以国防科技大学近年来在重力测量领域的研究为出发点,对国防科技大学在捷联式重力测量领域的研究现状进行了分析和总结。主要论述了捷联式重力测量的关键技术、研究历程、基本原理和典型试验结果,并对未来的发展方向进行了展望。     

Iterative Optimal Orthogonalization of the Strapdown Matrix

This paper treats the problem of finding an orthogonal matrix which is the closest, in the Forbenius norm, to a given nonorthogonal matrix. This nonorthogonal matrix is the result of a fast but rather inaccurate computation of the well-known direction cosine matrix (DCM) of a strapdown inertial navigation system. The known closed-form solution to this problem is rederived using the directional derivative method, and the conditions for minimum distance are derived and discussed. A new iterative technique for solving this problem is derived as a result of the application of the gradient projection technique and the directional derivative method. The practical computational problems involved in this technique are discussed. The new technique is demonstrated by three examples. Although particular attention is given to the 3 X 3 direction cosine matrix, the conclusions are nonetheless valid higher order matries.     

主动制冷型温控系统在捷联式重力仪上的应用

针对惯性导航系统内部惯性器件工作温度偏高的问题,以捷联式重力仪为研究对象,基于热电制冷器设计了一套主动制冷型温控系统.它可显著降低惯性器件工作环境温度及其变化率,有利于提升加速度计工作的温度稳定性和长期稳定性.根据系统仿真与实验验证,直接控制对象的温度能够稳定在30℃±0.05℃.与加热型温控系统相比,温差达到了-21.00℃,加速度计的工作环境温度从56.00℃降低到了43.59℃.主动制冷型温控系统能够提升重力仪在高温环境下的环境适应性,且其温度分布更加有利于提升加速度计的输出稳定性.     

激光陀螺实时抖动解调方法研究

为了实现激光陀螺实时抖动解调,与陀螺输出信号同步采样抖动反馈信号,并设计算法将两个信号的抖动分量相位和幅度对准,然后执行抖动剥除运算。这种实时解调算法不仅计算量小,而且没有附加相位延迟。     

The Psi-Angle Error Equation in Strapdown Inertial Navigation Systems

A detailed development is presented of the psi-angle vector differential equation as applied to the error analysis of strapdown inertial navigation systems. The coordinate systems involved and the psi misalignment vector are clearly defined. It is proven that apart from a sign change the psi-angle differential equation in the error analysis of strapdown inertial navigation systems is identical to the one used in conventional gimbaled inertial navigation systems.     

半球谐振陀螺全角模式控制技术研究

介绍了半球谐振陀螺全角模式的工作机理及其技术特点。对全角模式下振型的控制进行了理论分析,采用乘法相干解调对陀螺振型参数进行提取,并采用参数激励方法对谐振子进行驱动和控制。设计了数字电路进行实验,结果表明该全角模式控制技术实现了半球谐振陀螺的角速率积分功能,能够0°～360°全角度敏感输出,测得的角速度测量值超过300(°)/s,角度测量线性度优于10~(-4),与传统的力平衡模式相比,半球谐振陀螺的动态特性得到大幅提升。