一种圆锥运动条件下的等效旋转矢量算法研究

传统旋转矢量姿态算法一般采用陀螺的角增量信号来构造积分算法,当应用于输出为角速率的光纤陀螺捷联系统时,通过角速率提取角增量,算法会损失一定精度。提出了一种以陀螺角速率信号与角增量信号同时作为输入的改进旋转矢量姿态算法,进一步补偿了圆锥误差,提高了计算精度。仿真结果表明,该算法与传统二子样算法相比较,计算量相当,姿态精度、速度精度、位置精度有大幅度的提升。     

捷联惯性导航传统比力积分算法与对偶四元数算法的比较研究

捷联惯性导航速度更新算法中,将载体坐标系中的比力积分增量变换到导航参考坐标系中,载体姿态变化的影响通常采用一阶近似模型进行计算。本文分析了包括角振动和加速运动的动态运动下一阶近似模型的局限,在典型角振动及加速运动条件下对忽略姿态变化二阶项造成的速度更新误差进行了理论分析。通过比较,揭示了对偶四元数比力积分算法精度高于传统比力积分算法的原因,即和传统比力积分算法相比,对偶四元数比力积分算法等价于考虑了载体姿态变化影响的二阶项。通过典型角振动及加速运动条件下传统捷联惯性导航算法和对偶四元数导航算法的仿真比较,对理论分析结果进行了验证。     

基于角增量提取的旋转矢量算法研究

在某些由光纤陀螺或微机电陀螺组成的捷联航姿系统中,陀螺输出的是角速率。针对这种情况,归纳了基于角增量提取的二子样、三子样和四子样旋转矢量姿态算法,推导了这些算法的圆锥误差表达式,比较了它们的性能。     

Rotation method for direction finding via GPS carrier phases

A baseline rotation method is proposed for determining the direction of the baseline vector via Global Positioning System (GPS) carrier phase measurements. The space difference technique is adopted to resolve GPS carrier phase cycle ambiguities. Possible applications include the determination of the aiming directions of artillery rockets and the line of sights of tracking radars, etc. For such armaments, the direction findings are important and the rotating mechanisms are well equipped already. A general baseline vector which can be rotated on a two-degree-of-freedom platform is considered first. The relationship among the baseline vector and the two rotation axes is not known. A sequence of rotations is used to change the configuration of the system to find the direction of the baseline. Under different circumstances such as the cases that some orthogonal conditions among the unknown vectors are given, simplified algorithms are devised. To verify our method, software simulation and hardware experiments have been conducted. The simulation outcomes are used to determine the experimental parameters, such as the length of the baseline, the rotation angles etc. The results of repeated hardware experiments show that the sample standard deviation for the azimuth angle and the elevation angle of the 1.35 m baseline vector are 0.91 deg and 1.23 deg, respectively. The GPS receivers employed are Motorola ONCOREs. The errors of the estimated direction angles induced by the inaccuracy of rotation angles, which are unavoidable due to the imperfectness of the mechanical structure, are analyzed as well. Numerical examples for the error analysis are included     

Comparison of strapdown inertial navigation algorithm based on rotation vector and dual quaternion

 For the navigation algorithm of the strapdown inertial navigation system, by comparing to the equations of the dual quaternion and quaternion, the superiority of the attitude algorithm based on dual quaternion over the ones based on rotation vector in accuracy is analyzed in the case of the rotation of navigation frame. By comparing the update algorithm of the gravitational velocity in dual quaternion solution with the compensation algorithm of the harmful acceleration in traditional velocity solution, the accuracy advantage of the gravitational velocity based on dual quaternion is addressed. In view of the idea of the attitude and velocity algorithm based on dual quaternion, an improved navigation algorithm is proposed, which is as much as the rotation vector algorithm in computational complexity. According to this method, the attitude quaternion does not require compensating as the navigation frame rotates. In order to verify the correctness of the theoretical analysis, simulations are carried out utilizing the software, and the simulation results show that the accuracy of the improved algorithm is approximately equal to the dual quaternion algorithm.     

On the rotation vector differential equation

A direct and simple derivation of the differential equation of the rotation vector is provided. The property that the time derivative of the rotation vector and the angular velocity have equal magnitude along the direction of the rotation vector is also derived     

微电网三相负荷不平衡的量子遗传优化算法研究

为了解决微电网中普遍存在的三相负荷不平衡问题,详细分析了微电网三相负荷不平衡特征,提出了一种新的微电网三相负荷计算方法,并采用了改进型量子遗传算法对模型进行优化求解。所用的量子优化算法中引入了双链式结构和动态旋转角调整策略,提出了一种新的改进型量子遗传算法,并求解得出合适的解,从而获得最优的三相负荷接入方案。最后通过算例仿真验证了所提模型、策略和算法的有效性和可行性。     

RELATIONSHIPS FOR MOTION DESCRIBED IN ANY TWO ROTATIONAL REFERENCE FRAMES

In this paper the definitions of the relative derivatives of a vector with respect to time in any reference frame by using the notation of vectrix are proposed. It is further shown that with the help of vectrix one can treat the relative derivatives more clearly and more rigorously when multiple reference frames are concerned. Very useful relationships between the first order relative derivatives described in any two reference frames are derived. Relationships for the second order relative derivatives are also presented in detail. A new concept called "rotation induced acceleration" which is caused by the rotation of two reference frames when motion is necessarily described in them is presented. The result obtained in this paper is the generalization of the acceleration theorem given in conventional theoretical mechanics.     

飞机尾旋特性的综合数据分析法

为得到飞机的尾旋特性准确的非线性仿真结果,提出了新的综合数据分析方法,在气动力建模时采用综合因子,合理地将总角速度分解成沿速度矢的分量和沿３ 个体轴的分量,沿速度矢量的旋转角速度用于旋转天平试验数据;旋转角速度的其它分量用于振荡天平试验数据,综合地使用了各类试验数据。给出的不同类型的六自由度仿真结果表明,综合数据分析法的结果和试飞结果相当吻合。     

Cyclostationarity-exploiting direction finding algorithms

Many modulated communication signals exhibit a cyclostationarity (or periodic correlation) property, corresponding to the underlying periodicity arising from carrier frequencies or baud rates. By exploiting cyclostationarity, the signal direction of arrival (DOA) estimation can be significantly improved. We propose two new direction finding beamformer algorithms that exploit cyclostationarity. These algorithms show very attractive estimation performance over conventional beamforming methods, as depicted by simulation results.     

基于实数编码遗传算法的轨迹综合优化设计

提出了一种基于实数编码遗传算法的机构轨迹综合优化设计。在传统二进制编码遗传算法上进行改进,采用具有更快全局寻优能力的实数编码遗传算法对四杆机构各参数进行优化,从而得到机构最优解。运用MATLAB软件实现遗传算法优化设计,结果表明了此方法的有效性。     

Modeling and analysis of solar Doppler difference bias with arbitrary rotation axis

The solar rotation causes the solar Doppler difference bias, which leads to the decline of the velocity measurement accuracy. Modeling and compensation are an effective solution. The limited model with specific geometric direction, where the solar rotation axis is perpendicular to the plane through the Sun, the Earth and Mars, was established. However, in fact, the geometric relationship among the Sun, Mars and the spacecraft is not fully in line with the hypothesis of the model due to the spacecraft orbital angle and the solar rotation axis drift. Thus, this model is not consistent with the fact. In order to solve this problem, a universal solar Doppler difference bias model, which provides the expression with arbitrary rotation axis, is established in this paper. In this method, for any point at the solar surface, four variables including the direction of the solar rotation linear velocity at this point, the distance from this point to the rotation axis, the vector from this point to Mars, and the vector from this point to the spacecraft are calculated. Based on these four variables, the solar Doppler difference bias corresponding to this point is obtained. The theoretical analysis and simulation results demonstrate that the solar Doppler difference bias model with the actual rotation axis is different from that with one of the specific rotation axes. Therefore, it is indispensable to build the proposed model for compensation. Besides, the direction of the solar rotation axis, the spacecraft-Mars-Sun angle and the spacecraft-to-Mars distance are important impact factors for the proposed model.     

轴流压气机低转速特性表达方式的改进及应用

针对常规压气机特性图在低转速区域适用性较差的问题,首先给出一种改进的轴流压气机特性表达方法,在特性模型中用基于出口气流参数的换算转速代替基于进口气流参数的换算转速。然后将这种改进应用于压气机低转速特性的外推估算分析,结合压气机零转速特性线的特点,提出了基于改进特性图的外推方法,并给出了外推结果的合理性判断准则。实例表明,改进后的特性图非常适合表达发动机起动和风车状态的压气机特性,在该图上进行低转速特性的外推计算行之有效且结果准确性高,很好地解决了压气机低转速特性难以获取的难题。     

基于遗传退火算法的电路模拟吸波材料设计

相比传统吸波材料,电路模拟吸波材料可以很好地减小材料厚度、提高吸波性能,其设计通常使用遗传算法进行优化。针对传统遗传算法的诸多不足,对交叉和变异概率进行了改进、引入了模拟退火思想作为子代接受准则并增加了算法终止准则。其中,对交叉和变异概率的改进是最大创新点。改进后的遗传算法只需进化100代即得到最优解,平均反射率为-15.0420,厚度为1.43 mm,均优于传统算法得出的结果。结果表明,改进后的遗传算法具有收敛速率快、不易陷入局部最优解等优点。     

应用SVM的发动机故障诊断若干问题研究

支持向量机能够克服一般神经网络容易出现的过学习和泛化能力低等不足。提出一种基于支持向量机的航空发动机气路部件故障诊断方法,讨论了支持向量机的核函数选择和参数确定问题,并对"块算法"进行了分析。仿真实验表明,设计的正则化参数和核参数合理,故障分类器具有良好的分类准确性和泛化性能,可以对发动机气路部件的典型故障进行正确诊断。     

基于SVM辨识的涡扇发动机全包线稳态控制方法

针对涡扇发动机全飞行包线范围稳态最优控制器的设计问题,首先根据不同飞行条件下发动机各工作状态的稳态“小偏差”线性模型,采用线性二次型调节器(LQR)分别设计得到相应的发动机最优线性控制器参数,然后将所得到的线性控制器用支持向量机方法进行非线性逼近,得到控制器参数的支持向量机辨识模型,以满足发动机全包线、全状态稳态控制的需要.支持向量机模型的输入为飞行高度、马赫数和稳态转速,输出为线性控制器参数.应用实例表明:该方法在全包线范围内对发动机最优稳态控制器的逼近误差均在2%以内,能较好满足控制精度要求.      

Outlier resistant adaptive matched filtering

Robust adaptive matched filtering (AMF) whereby outlier data vectors are censored from the covariance matrix estimate is considered in a maximum likelihood estimation (MLE) setting. It is known that outlier data vectors whose steering vector is highly correlated with the desired steering vector, can significantly degrade the performance of AMF algorithms such as sample matrix inversion (SMI) or fast maximum likelihood (FML). Four new algorithms that censor outliers are presented which are derived via approximation to the MLE solution. Two algorithms each are related to using the SMI or the FML to estimate the unknown underlying covariance matrix. Results are presented using computer simulations which demonstrate the relative effectiveness of the four algorithms versus each other and also versus the SMI and FML algorithms in the presence of outliers and no outliers. It is shown that one of the censoring algorithms, called the reiterative censored fast maximum likelihood (CFML) technique is significantly superior to the other three censoring methods in stressful outlier scenarios.     

修正Rodrigues参数在飞行器定姿中的应用(英文)

There are two attitude estimation algorithms based on the different representations of attitude errors when modified Rodrigues parameters are applied to attitude estimation. The first is multiplicative error attitude estimator （MEAE）, whose attitude error is expressed by the modified Rodrigues parameters representing the rotation from the estimated to the true attitude. The second is subtractive error attitude estimator （SEAE）, whose attitude error is expressed by the arithmetic difference between the true and the estimated attitudes. It is proved that the two algorithms are equivalent in the case of small attitude errors. It is possible to describe rotation without encountering singularity by switching between the modified Rodrigues parameters and their shadow parameters. The attitude parameter switching does not bring disturbance to MEAE, but it does to SEAE. This article introduces a modification to eliminate the disturbance on SEAE, and simulation results demonstrate the efficacy of the presented algorithm.     

Interlaced Kalman filtering of 3D angular motion based on Euler'snonlinear equations

A novel Kalman filtering technique is presented that reduces the mean-square-error (MSE) between three-dimensional (3D) actual angular velocity values and estimated ones by an order of magnitude (when compared with the MSE resulting from direct measurements) even under extremely low signal-to-noise ratio conditions. The filtering problem is nonlinear in nature because the dynamics of 3D angular motion are described by Euler's equations. This nonlinear set of differential equations state that the angular acceleration in one axis is proportional to the torque applied to that axis, and to the products of angular velocity components in the other two axes of rotation. Instead of using extended Kalman filtering techniques to solve this complex problem, the authors developed a new approach where the nonlinear Euler's model is decomposed into two pseudolinear models (primary and secondary). The first model describes the time progression of the state vector containing the linear terms, while the other characterizes the propagation of the state vector containing the nonlinearities. This makes it possible to run two interlaced discrete-linear Kalman filters simultaneously. One filter estimates the values of the state vector containing the linear terms, while the other estimates the values of the state vector containing the nonlinear terms in the system. These estimates are then recombined, solving the nonlinear estimation process without linearizing the system. Thus, the new approach takes advantage of the simplicity, computational efficiency and higher convergence speed of the linear Kalman filter form and it overcomes many of the drawbacks typical of conventional extended Kalman filtering techniques. The high performance and effectiveness of this method is demonstrated through a computer simulation case study     

用Walsh函数方法的阶梯波式DC/AC变换器的设计与实现

讨论了阶梯波式 DC/AC变换器的一种新的设计与实现方法 ,即用 Walsh函数方法及矢量合成原理分析、综合和设计。试验结果表明实现了逆变器结构的简化及其输出电压频率稳定 ,幅值便于调节与自动稳定。给出了有关硬件、软件框图与说明、试验结果及进一步设想