基于GPS与惯性组件的复合测姿系统设计

针对微小型载体空间有限而无法安装大型测姿系统,提出了一种低成本的微型复合测姿方案.复合测姿系统由单天线GPS和MEMS惯性组件构成.利用扩展卡尔曼滤波将单天线GPS和MEMS惯性组件信息融合,提高了姿态估计精度.室外车载实验结果表明,利用该复合测姿系统解算的滚角和俯仰角误差可控制在1°以内,航向角误差可控制在2°以内.     

GPS测姿系统仿真实验研究

众所周知,海上、空中、陆地上的运动物体往往需要知道其姿态,并根据其姿态进行实时控制。采用惯性系统来实现的测姿,设备复杂,价格昂贵,难以推广,而研究的以GPS接收机为基础的多天线姿态测定系统正克服了这些缺点。着重阐述了单历元GPS测姿算法,通过提取两个独立的GPS OEM传感器来接收信号进行差分计算,从原始数据消除误差后解算出载体的指向。这种由两块单频接收机和信号处理器实现的差分测姿系统有很好的应用前景。     

圆度误差的最小二乘法、最小包容区域法和最优函数法评定精度之比较

目的在于寻找符合最小条件的圆度误差评定方法。首先详细介绍圆度误差评定的最小二乘法、最小包容区域法和最优函数法的算法模型与实现方法;然后,在三坐标测量机上对被测圆进行采样点坐标数据提取,分别用最小二乘法、最小包容区域法和最优函数法对给定圆进行误差评定。结果表明,最小包容区域法评定精度最高,最优函数法评定精度次之,最小二乘法评定精度较低。     

GPS在船舶姿态测量中的应用

在本文介绍的测姿方案中,采用GPS接收机对船舶载体姿态测量应用方面进行了研究。其研究方向主要集中在对船舶载体姿态进行测量,并利用现有试验条件进行了尝试,确定船的偏航角、横滚角、俯仰角,最终确定船舶的姿态与时间的关系。目前,建立在相对定位基础上的GPS导航技术己经成熟,随着载波相位动态跟踪技术的发展,以此为基础的GPS测姿系统将逐渐显现出其巨大的潜力和优越性。因此,其应用前景是十分广阔的。     

Indoor GPS工业测量系统自标定技术研究

Indoor GPS工业测量系统在进行测量前必须标定各发射头之间的相对位置关系及其空间姿态,针对此自标定问题,采用单个圆柱型传感器配合标准尺进行测量,获得空间点相对于各发射头中心的水平方位角和垂直方位角,在此基础上建立了基于角度值的坐标参数转换模型,采用非线性最小二乘法进行解算以完成Indoor GPS的自标定。实验证明该方法简便可行。     

基于MEMS传感器的高精度姿态角测量研究

针对传统姿态参考系统姿态解算容易受到载体运动加速度的干扰,导致系统精度变低、稳定性变差等问题,提出一种改进的卡尔曼滤波算法。该算法建立基于四元数的惯性系统姿态解算数学模型,并根据载体运动加速度的大小,适时调整卡尔曼滤波器的量测噪声方差的大小,以此减弱卡尔曼滤波过程中运动加速度对姿态角解算精度的影响。采用MEMS三轴陀螺仪、加速度计和磁阻传感器完成载体在电梯升降过程中的测量,对实验测量数据进行姿态解算,结果表明改进后的卡尔曼滤波算法能够有效减小运动加速度对姿态解算的影响,姿态角的均方根误差相对于传统的姿态参考系统降低约40%。     

GPS双星航姿测量研究

提出用两部测量型GPS接收机，实时观测两颗以上GPS卫星在站心坐标系下的高度角，方位角和载波相位，来推算基线（船线）的航向和姿态，初步解决了整周模糊度的解算问题，文中对影响航向和姿态准确解算的因素进行了分析，并提出了改进的办法。     

主动全向浮标阵的定位解算方法

推导出一种利用加权最小二乘法解算多枚浮标的定位结果的方法,对其性能进行了数值仿真分析,并与最小二乘法进行了比较。仿真结果表明,加权最小二乘法的性能较最小二乘法的性能有所提高,证明了算法的有效性。     

激光跟踪仪测角精度评定方法

本文以Leica AT901＿B激光跟踪仪为测试仪器,进行测角精度的评定研究。由于缺乏严密的角度检校标准,本文参考经纬仪／全站仪系统检校规范,提出以常规的角度检校模型为基础,采用全圆方向观测法获取数据,通过坐标反算观测值来计算系统轴系误差2C值和I角误差,并通过最小二乘平差原理解算系统水平角误差和垂直角误差。该方法基于严密的经纬仪／全站仪角度检校模型,真实地反映了激光跟踪仪的轴系误差和测角精度。通过数据的平差解算,求得AT901＿B的水平和垂直测角精度分别为0．54″和0．52″,由此评定出AT901＿B激光跟踪仪的实测精度符合其标称精度。     

用微机辅助判别圆弧线轮廓度合格性

本文介绍利用微机辅助计算确定圆弧线轮廓度合格性的判别法和计算相应圆心坐标数据的处理方法,由此可使从经最小二乘法初算通常判为不合格的测件中选出合格件。     

A sequential linear least square algorithm for tracking dynamic shapes of smart structures

This paper presents a sequential linear least square algorithm for tracking dynamic shapes of piezoelectric smart structures. The dynamic shape discussed in this paper is defined as a host structural shape varying with time, and the tracking technique is to find an electric voltage history for each piezoelectric device over a time period so that the desired structural movements can be achieved. In the theoretical formulation, dynamic equations of piezoelectric smart structures are introduced by finite element analysis, and then a solution procedure for a set of time‐dependent electric voltages is derived by combining the linear least square method and the Houbolt numerical integration scheme. The formulation indicates that this algorithm can be used to find the time‐dependent voltages for tracking structural movements of piezoelectric smart structures. The present novel formulation is then demonstrated through numerical examples for tracking dynamic shapes of piezoelectric smart beams and plates. The numerical results for the smart beam are compared with the experimental ones. It is shown that the present sequential linear least square algorithm is capable of efficiently simulating dynamic shape tracking for smart structures. Copyright © 2006 John Wiley & Sons, Ltd.     

一种新的模拟电路故障模糊集确定算法

提出了一种在模拟电路故障诊断中故障类模糊集的确定算法．该算法基于测前仿真法,不但同时适用于线性电路和非线性电路,而且可以确定元件模糊组以外的故障类模糊集．算法利用电路仿真故障特征数据计算故障的类间差异矩阵,从而完成故障类模糊集的确定．计算示例验证了该算法的有效性．     

基于MEMS惯性传感器的微型姿态测量系统

提出了一种基于低成本MEMS惯性传感器的微型姿态测量系统,包括MEMS速率陀螺、MEMS磁强计、单轴MEMS加速度传感器.重点研究了基于扩展Kalman滤波（EKF）的姿态估计创新算法,通过速率陀螺更新误差状态四元数计算姿态角,并通过飞行方向的加速度传感器和三轴磁强计来补偿陀螺漂移和姿态角误差,利用扩展卡尔曼滤波方程消除瞬时干扰,实现高动态姿态测量.系统的仿真和高动态实验表明,姿态测量动态精度低于5°,静态精度低于0.7°.     

阻尼矩阵选取对核电厂结构地震响应的影响分析

已有研究表明时程动力法中阻尼矩阵的确定对复杂结构工程的地震响应有明显的影响,而核电厂安全相关结构在抗震分析时通常采用时程动力法。为研究阻尼矩阵的选取对核电厂结构的地震响应的影响,从比例阻尼拟合的精度出发,基于结构不同振型对结构产生的影响程度入手,建立更为精确的结构阻尼模型,即等效比例阻尼,并进一步考虑结构自振特性以加权最小二乘法拟合确定等效比例阻尼系数,提出了核电厂结构地震响应分析相应的计算方法。计算结果表明,该方法较传统比例阻尼的方法更接近精确解,是核电工程抗震分析的一个实用参考应用。     

飞航导弹高精度自适应预测控制设计

飞航导弹的飞行主要是通过姿态稳定与调节来实现的。通过以小扰动模型为基础的导弹动力学特性分析，建立了导弹姿态控制回路的串级控制结构，并且以离散模型作为基于递推最小二乘法的自适应预测控制的被控对象，把原先响应较慢的质心控制转换为反应较快而且精度高的弹道角控制。根据导弹的特性，在姿态内回路采用广义预测控制，在弹道外回路采用一种积分形式的预测控制。在参考信号上，实现了质心指令到弹道指令的有效变换，为高精度小超调跟踪奠定了基础。这种方法实现了姿态参考信号与导引指令的统一，姿态控制与质心控制的统一，充分降低了对气动等     

Problem of ambiguity in the determination of optical constants of thin absorbing films from spectroscopic reflectance and transmittance measurements

We propose a new and simple procedure to overcome the ambiguity in the determination of optical constants of thin absorbing films from spectroscopic reflectance and transmittance measurements. The basis for the proposed method is an error analysis with the help of an error simulation technique and an error variation technique. We show that in practice (owing to experimental errors) it is not possible to overcome the problem of ambiguity by normal-incidence spectroscopic measurements alone. At least one oblique-incidence measurement is necessary for unambiguously determining the optical constants of the film. We discuss the consequences of experimental errors of the measured transmittance and reflectance values for the determination of the optical constants.     

Simulation analysis of dynamic working performance for star trackers

The elongated imaging track pertaining to a star spot recorded in the image sensor of a star tracker will diffuse over several pixels at a high angular velocity, leading to an inaccurate, even false, attitude value. A computer simulation of the attitude determination from a dynamic star tracker is developed first, based on a dynamic mathematical model of the star-spot imaging and an efficiency validation of the star centroiding algorithm in the dynamic condition. Then major error sources affecting the attitude accuracy in the dynamic condition are analyzed and discussed systematically based on the simulation results. A mathematical model calculating the average star number detected in the field of view is also deduced, using simulation results and signal processing theory, with image trailing ranging from 0 to 20 pixels during exposure. The summarized regularity is helpful in the system design and accuracy evaluation of a star tracker.     

EMD与SLS法在爆破振动加速度信号时域积分中的应用

实测差异分析表明,速度振幅峰值分布受外界因素影响更具规律性,加速度信号主频分布比速度信号更分散。提出一种加速度信号时域积分算法,先基于经验模态分解法对信号进行趋势项剔除、去均值化和高频降噪,再对存在漂移现象的各固有模态函数分量时域积分速度分量进行最小二乘法处理。研究表明:各固有模态函数分量在处理过程中应分别对待;为达到较好降噪效果,阈值修正系数k应不断调整;分段最小二乘法对漂移现象的消除能力优于单段最小二乘法和经验模态分解法。最后,通过本文定义的全局参量和局部参量验证算法的优越性。     

基于改进最小二乘步骤的NARMA模型辨识非线性时变结构系统

基于时变非线性自回归滑动平均模型利用改进的递推最小二乘算法提出一种用于非线性时变结构系统辨识的方法。利用线性变换将非线性时不变结构系统的动力学模型转化为非线性自回归滑动平均模型,然后将非线性项展开为系统输出数据的多项式的形式。利用短时时不变假设,通过改变模型的参数跟踪系统参数的变化,将非线性时变系统的辨识问题转化为线性时变系统的辨识问题,再利用改进的递推最小二乘算法实现对非线性时变结构系统的辨识。最后通过一个具有非线性时变刚度的三自由度结构系统的仿真算例表明,该方法可以有效地辨识非线性时变结构系统。     

Estimation of Attitude and External Acceleration Using Inertial Sensor Measurement During Various Dynamic Conditions

This paper proposes a Kalman filter-based attitude (i.e., roll and pitch) estimation algorithm using an inertial sensor composed of a triaxial accelerometer and a triaxial gyroscope. In particular, the proposed algorithm has been developed for accurate attitude estimation during dynamic conditions, in which external acceleration is present. Although external acceleration is the main source of the attitude estimation error and despite the need for its accurate estimation in many applications, this problem that can be critical for the attitude estimation has not been addressed explicitly in the literature. Accordingly, this paper addresses the combined estimation problem of the attitude and external acceleration. Experimental tests were conducted to verify the performance of the proposed algorithm in various dynamic condition settings and to provide further insight into the variations in the estimation accuracy. Furthermore, two different approaches for dealing with the estimation problem during dynamic conditions were compared, i.e., threshold-based switching approach versus acceleration model-based approach. Based on an external acceleration model, the proposed algorithm was capable of estimating accurate attitudes and external accelerations for short accelerated periods, showing its high effectiveness during short-term fast dynamic conditions. Contrariwise, when the testing condition involved prolonged high external accelerations, the proposed algorithm exhibited gradually increasing errors. However, as soon as the condition returned to static or quasi-static conditions, the algorithm was able to stabilize the estimation error, regaining its high estimation accuracy.