基于模糊卡尔曼滤波的姿态估计算法

针对载体运动情况下由于运动加速度引起的载体姿态估计误差,提出了一种基于模糊控制与卡尔曼滤波相结合的姿态估计算法。以加速度计采集值作为模糊控制器输入,自适应地估计卡尔曼滤波量测噪声方差。通过静止、转动及运动实验采集加速度计和陀螺仪数据,分别使用互补滤波法、梯度下降法和模糊卡尔曼滤波法进行姿态估计,结果表明模糊卡尔曼滤波在运动情况下准确性大幅提高,在静止、转动和运动下均具有更好的实时性。     

四旋翼飞行器互补滤波姿态求解器的设计

精确的姿态角在四旋翼飞行器稳定飞行中起着非常重要的作用,为了实现小型低成本四旋翼飞行器高精度姿态数据的输出,搭建了STM32F103、MPU6050和气压计组成的姿态检测系统。并基于四元数微分方程,提出了一种PI改善型互补滤波姿态求解器的设计算法。该算法对陀螺仪测量数据进行了高通滤波、对加速度计和磁力计测量数据进行了低通滤波,提高了姿态解算精度。最后,通过实验平台将测量的PI改善型互补滤波算法与普通互补滤波算法四旋翼姿态角进行了比较分析,实验结果表明,PI改善型互补滤波算法求解器的姿态角动态误差较小,性能更稳定,能够满足小型低成本四旋翼飞行要求。     

基于四元数二阶互补滤波的四旋翼姿态解算

姿态解算是四旋翼飞行器的关键技术,其精度直接影响飞行器控制的可靠性和稳定性。针对当前常用一阶互补滤波算法中阻带衰减速率慢和陀螺仪常值漂移产生的稳态误差问题,通过增加积分环节,设计了一种基于四元数的二阶互补滤波算法,能更好地利用加速度计和磁力计的稳态信息有效补偿陀螺仪常值漂移,从而减少姿态解算的累积误差。仿真结果表明,该算法具有更好的稳定性,提高了系统的姿态解算精度。通过飞行器真实飞行数据对算法进行了实验验证,结果显示姿态的俯仰角、横滚角精度1°,偏航角精度2°,能很好地满足飞行器控制系统对姿态解算的精度要求。     

动态倾角传感器及其传递特性的研究

通过分析惯性传感器在姿态检测系统中的优缺点,提出一种简易互补滤波算法对陀螺仪和加速度计进行数据融合,生成动态倾角信号.利用角度测试装置测试该基于互补滤波的倾角传感器的动态特性,通过系统辨识获取该传感器的传递函数.辨识结果表明,该动态倾角传感器有效去除加速度计动态情况下的干扰和陀螺仪累积漂移误差,及时跟踪系统倾角变化,得到比较准确的动态角度值.     

基于偏振光传感器的无人机姿态组合滤波算法北大核心CSCD

针对惯性导航易受运动加速度影响和GPS与磁力计导航易受到电磁干扰影响等问题,提出了一种偏振光辅助惯性导航的无人机航姿估计算法。利用大气瑞利散射模型获取最大偏振矢量,辅助惯性元件实现了基于PI互补滤波的姿态四元数更新算法;对陀螺仪、加速度计和偏振光传感器信号进行粒子滤波的融合修正。实验结果表明:该方法解算的姿态角在静态条件下性能稳定,抑制了传感器噪声;同时在运动情况下准确性大幅提升,具有更好的动态解算精度。     

改进时域盲解卷积算法在轴承故障诊断中的应用

针对实际工业现场强背景噪声、干扰源多、旋转机械故障盲提取算法的不足,为了有效提取并分离出轴承的故障特征,提出一种基于广义形态滤波和改进KL距离相结合的改进时域盲解卷积故障特征提取算法。首先利用广义形态滤波提取信号中重要特征频率;然后利用正交匹配追踪算法去除滤波后信号的周期成分;最后,使用改进KL距离计算各分量的距离,通过模糊C均值聚类获得分离信号。实验仿真和故障滚动轴承声信号及振动信号的分析结果表明,该方法能够有效提取滚动轴承故障特征。     

惯性传感器和互补滤波器在姿态估计中的应用

惯性测量方法被广泛应用于机器人等运动物体的姿态检测中,本次研究利用惯性传感器和互补滤波器的优点进行姿态估计。为了获取互补滤波器的转接频率,进行了加速度计和陀螺仪的动态响应测试,设计了自适应互补滤波器。在双轮直立行走机器人装置上对方案进行了验证,实验数据表明,利用自适应互补滤波算法可以准确可靠的获取机器人的姿态信息。     

全向AGV的优化互补滤波姿态解算

针对单一的MEMS陀螺仪无法解决本身的易发散和磁力计易受磁场干扰导致引入新的噪声,而带来的姿态估计不精确的问题,提出了一种基于全向AGV的优化互补滤波的姿态解算方法.偏航角不参与四元数解算,在水平姿态角四元数解算的基础上,利用共轭梯度法减小陀螺仪的漂移误差.再引进经过椭球修正后的磁力计数据作为观测量,与偏航角进行一阶互补滤波融合,并确定加权因子.搭建了基于STM32和MEMS传感器为核心的全向AGV实验平台,实验结果表明,该方法能有效抑制陀螺仪易发散和磁力计易受干扰的问题,提高姿态解算的精确性,使姿态解算具有良好的动态和静态性能,同时保证了系统的稳定性.     

基于小波神经网络修正自适应滤波的钻具姿态解算研究

针对惯性随钻测量中，由于钻头振动导致系统三轴加速度计数据失真，从而使得解算的钻头姿态角误差较大的问题。提出一种基于小波神经网络(WNN)与自适应滤波(AKF)联合对钻具姿态进行估计的方法，首先建立钻具姿态自适应滤波的状态空间模型，根据估计后的残差不断调整自适应因子，降低姿态的估计误差，提高钻具姿态估计精度；根据滤波器的输入输出建立小波神经网络模型，对比输出误差在线修正网络模型，对姿态信息进行反馈补偿。设计振动台实验以及钻进实验对所提方法验证，其中钻进实验中井斜角误差降低到±1.8°，实验结果表明，所提方法解算精度优于自适应卡尔曼滤波算法，能够有效抑制振动误差对姿态解算的影响，为实际钻井提供理论依据。     

一种基于MPU9250的四旋翼姿态解算改进算法

针对四旋翼飞行器MEMS惯性测量单元姿态估计过程中存在的漂移和噪声问题,提出了一种基于互补滤波的改进算法。建立了以MPU9250为姿态测量单元的四旋翼飞行器测试平台。分别在静态和动态条件下,收集和比较了不同方法获得的姿态数据,包括信息融合的卡尔曼滤波算法,传统互补滤波的数据融合,以及改进的滤波融合算法。实验结果表明,改进的姿态融合算法在不同条件下具有较高的估计精度和最终姿态角的漂移和噪声误差较小的优点,易于在低成本的飞机控制系统中实现。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...