用四元数状态切换无迹卡尔曼滤波器估计的飞行器姿态

在较大初始姿态误差角下, 针对捷联惯导/CCD星敏感器(strap-intertial navigation system/CCD star sensor, SINS/CCD)姿态估计系统扩展卡尔曼滤波(extended Kalman filter, EKF)算法精度下降的问题, 提出了基于四元数的状态切换无迹卡尔曼滤波算法. 通过状态实时切换降低了全维无迹卡尔曼滤波(unscented Kalman filter, UKF)的维数, 减小了计算复杂度, 提高了系统的实时性. 文中采用基于特征向量求解的代价函数法计算四元数均值避免了UKF算法中四元数规范化的限制; 利用乘性误差四元数表示姿态更新点与估计点之间的距离, 解决了四元数协方差阵奇异性问题. 仿真实验结果表明: 与EKF相比, 该算法在精度上有较大提高; 与全维UKF算法和修正罗德里格斯参数UKF算法相比, 该算法精度相当但估计时间均有不同程度的减少.     

基于四元数衍生无迹卡尔曼滤波的二段式多旋翼无人机姿态估计算法

对传统多旋翼无人机姿态估计算法难以兼顾高精度、强实时性以及抗干扰能力差的问题,首先基于一种计算量较小的衍生无迹卡尔曼滤波算法,在量测更新中,将加速度数据和磁力计数据分为两个阶段进行姿态四元数校正处理,然后从旋转四元数的本质出发,推测出四元数各元素分别包含着不同的姿态角信息,最后将校正四元数分别乘上为降低校正过程中的相互干扰所设计的系数,提出一种基于四元数衍生无迹卡尔曼滤波的二段式多旋翼无人机姿态估计算法.通过使用PIXHAWK飞控数据,与传统姿态估计算法进行仿真实验对比,实验表明,本文提出算法与传统使用扩展卡尔曼滤波(EKF)或无迹卡尔曼滤波(UKF)的姿态估计算法相比,在实时性、解算精度和抗干扰能力方面有较大提升.     

Rotation estimation for mobile robot based on single-axis gyroscope and monocular camera

The rotation matrix estimation problem is a keypoint for mobile robot localization, navigation, and control. Based on the quaternion theory and the epipolar geometry, an extended Kalman filter (EKF) algorithm is proposed to estimate the rotation matrix by using a single-axis gyroscope and the image points correspondence from a monocular camera. The experimental results show that the precision of mobile robot s yaw angle estimated by the proposed EKF algorithm is much better than the results given by the image-only and gyroscope-only method, which demonstrates that our method is a preferable way to estimate the rotation for the autonomous mobile robot applications.     

A Filtering Approach Based on MMAE for a SINS/CNS Integrated Navigation System

This paper explores multiple model adaptive estimation (MMAE) method, and with it, proposes a novel filtering algorithm. The proposed algorithm is an improved Kalman filter-multiple model adaptive estimation unscented Kalman filter (MMAE-UKF) rather than conventional Kalman filter methods, like the extended Kalman filter (EKF) and the unscented Kalman filter (UKF). UKF is used as a subfilter to obtain the system state estimate in the MMAE method. Single model filter has poor adaptability with uncertain or unknown system parameters, which the improved filtering method can overcome. Meanwhile, this algorithm is used for integrated navigation system of strapdown inertial navigation system (SINS) and celestial navigation system (CNS) by a ballistic missile's motion. The simulation results indicate that the proposed filtering algorithm has better navigation precision, can achieve optimal estimation of system state, and can be more flexible at the cost of increased computational burden.      

Minimum-Order Kalman Filter With Vector Selector for Accurate Estimation of Human Body Orientation

This paper describes a new quaternion-based Kalman filter (KF) for estimating human body orientation using an inertial/magnetic sensor. The proposed algorithm is comprised of a quaternion measurement step and a KF step that are connected in feedback relationship. This allows the algorithm to have a minimum-order structure (i.e., fourth order) that is computationally very efficient. Furthermore, to offer more reliable information to the quaternion measurement step, a vector selector scheme is adopted, which effectively adds the gyro measurement to the so-called Wahba's problem that conventionally uses only the accelerometer and magnetometer measurements. This protects the algorithm against undesirable conditions such as fast movements and temporary magnetic disturbances, enabling it to compute an accurate orientation estimate. Due to the computational efficiency of the algorithm, it is suitable for real-time ambulatory human motion tracking applications that require multiple and untethered inertial/magnetic sensors with low-cost onboard processing.     

EKF与互补融合滤波在姿态解算中的研究

传统的信号滤波方法不能有效的融合多传感器测量数据,或者融合中失去过去信号状态信息.针对这一问题,提出了扩展卡尔曼滤波(Extended kalman filtering,EKF)与互补滤波融合的信号处理策略.借助STM32微处理器采集MPU9250惯性测量传感器的原始数据,运用多传感器信息融合的处理算法,比较了互补滤波姿态解算结果和对互补滤波过程中所得的四元数运用EKF矫正后进行姿态解算的结果,以及互补滤波解算的欧拉角运用EKF矫正后的姿态数据.通过实验中3种解算结果与理论值的对比,得出结论:采用互补滤波会存在一定超调量,且结果波动较大,存在较大的噪声,对互补滤波过程中的四元数进行EKF滤波虽能降低解算结果的噪声,但仍存在超调量.而应用EKF矫正互补滤波解算出的欧拉角能同时解决超调量和降低噪声误差,抑制了随机波动,起到了更好的解算效果.     

Experimental studies of the use of phase lead filters to compensatelags in head-coupled visual displays

Display lags degrade performance when using the head to track a target presented on a helmet-mounted display. These lags originate from delays in measuring the position of the head and the time required to generate the image of the target. This paper presents two laboratory studies on the use of phase lead filters to improve head tracking performance in the presence of display lags. In the preliminary study, the benefits of lag compensation by a phase lead filter were impeded by associated changes in filter gain. The frequency responses of two phase lead filters were then optimized to have near unity gain at frequencies below 0.7 Hz where there was most head motion. The main study showed that these optimized filters significantly improved head tracking performance with a system having a total lag of 140 ms. At frequencies above about 0.7 Hz, a greater than unity filter gain caused jittery image movement. Although this jittering degraded head tracking performance it was removed by an alternative lag compensation technique involving `image deflection'. This deflection shifted the displayed image to its correct horizontal and vertical position relative to the head. Image deflection, combined with the phase lead filters, produced a tracking performance unaffected by lag     

动态模型偏差校正在列车组合定位中的应用

扩展卡尔曼滤波(Extended Kalman filter, EKF)的准确性依赖于观测的质量、观测对象的非线性程度及动态模型的准确性. 该方法通常假设其动态模型是不变的, 而且默认为非线性程度较弱, 这些在实际的车辆运动中都是不可靠的处理方式. 本文提出了一种利用最小二乘支持向量机(Least squares support vector machine, LSSVM)的技术增强扩展卡尔曼滤波的新算法. LSSVM改进后的EKF算法(LSSVM-EKF)一定程度上弥补了EKF处理强非线性问题的不足; 而且可以自适应地估计历史数据的动态建模偏差, 并使用估计偏差来补偿动态模型. 开发了一种引入Allan方差的K折交叉验证方法来确定LSSVM的训练参数; 将动态模型偏差通过有限数据集与LSSVM一起训练; 并引入无损变换将LSSVM与EKF进行了集成. 为了验证算法, 最后设计了车载试验, 并采用列车数据验证了文中所提的方法, 结果表明LSSVM-EKF可以较好地适应实际车辆运动环境, 可以提供一种可用的车辆定位方法.     

基于MAEKF算法的航姿参考系统设计

构建了以低成本MEMS陀螺仪、加速度计和磁传感器组合的航姿参考系统,提出了一个乘性自适应扩展卡尔曼滤波算法.取乘性误差四元数和陀螺仪误差作为状态量,基于重力场和磁场构造了量测矢量,用于修正航姿数据.并采用准确量测法,给滤波器加入了四元数的归一化约束,最后给出了基于新息的估计量测噪声方差矩阵的公式.通过仿真和试飞验证,表明本文设计的低成本的航姿参考系统能够提供比较准确的航姿信息.与常规的扩展卡尔曼滤波器比较,本文设计的乘性自适应扩展卡尔曼滤波算法有效提高了系统的精度和稳定性,并且具有较好的鲁棒性.     

柔性自激异步发电系统反演自适应滑模控制

为抑制宽转速范围条件下柔性自激异步发电系统(FS–CAGS)电压定向谐波干扰,提高FS–CAGS鲁棒稳定控制能力,实现功率快速跟踪控制,采用扩展卡尔曼滤波EKF电压定向与反演自适应滑模控制相结合的方法,提出一种EKF电压定向反演自适应滑模直接功率控制新方法.军用底盘集成式直流微电网中FS–CAGS控制仿真实验结果表明,在负载冲击扰动和宽转速突变条件下,相对于传统直接电压定向精确反馈线性化鲁棒控制方法,新控制方法可加快直流输出电压稳定速度,减小电压超调,提高功率跟踪速度, FS–CAGS电流谐波抑制和鲁棒稳定能力得到加强.     

Efficient algorithms of clustering adaptive nonlinear filters

This paper proposes a new class of efficient adaptive nonlinear filters whose estimation error performance (in a minimum mean square sense) is superior to that of competing approximate nonlinear filters, e.g., the well-known extended Kalman filter (EKF). The proposed filters include as special cases both the EKF and previously proposed partitioning filters. The new methodology performs an adaptive selection of appropriate reference points for linearization from an ensemble of generated trajectories that have been processed and clustered accordingly to span the whole state space of the desired signal. Through a series of simulation examples, the approach is shown significantly superior to the classical EKF with comparable computational burden     

自适应渐消有偏扩展卡尔曼滤波在目标跟踪中的应用

针对机动目标跟踪过程观测矩阵病态导致扩展卡尔曼滤波算法跟踪效果不佳的问题,提出一种自适应渐消有偏扩展卡尔曼滤波算法。该算法以扩展卡尔曼滤波为基本框架,并借鉴Gauss-Markov模型的思想以解决观测矩阵病态问题。算法根据状态估计均方误差最小条件求得有偏因子,以降低病态观测矩阵对滤波估计的影响;根据滤波发散判据提出一种新的渐消因子估计方法,以实时调整预测协方差矩阵,从而改善滤波增益并有效提高目标跟踪精度。仿真结果表明,改进算法比传统扩展卡尔曼滤波对目标跟踪的精度有较大提高,同时稳定性更好。     

状态切换CDKF算法及其在低成本紧组合导航系统中的应用

成本SINS/GPS紧组合导航系统在大失准角情况下出现的滤波发散现象,建立了基于乘性四元数的非线性导航系统误差模型,并提出一种基于乘性四元数的状态切换中心差分卡尔曼滤波算法.该算法通过在均值四元数计算过程中引入修正的罗德里格参数进行状态切换,解决了传统中心差分卡尔曼滤波算法中对于四元数正交规范化的限制.仿真实验结果表明,本文提出的方法能够有效实现对于载体运动状态的在线估计,且与无迹卡尔曼滤波算法相比,具有更高的滤波精度.     

CDKF在车载捷联惯导自对准中的应用

研究了车载捷联惯导在大方位失准角下的静基座自对准。采用Sigma点卡尔曼滤波,根据均值与协方差信息按非线性映射传播的特点,直接利用非线性模型,可以消除EKF存在的需要解析Jacobi矩阵以及将非线性系统线性化后的系统模型误差问题不易调整的弊端,其中的中心差分卡尔曼滤波(CDKF)精度高,且对状态协方差阵不敏感。仿真结果表明,在大方位失准角下采用CDKF进行初始对准,比用传统的EKF更精确且收敛速度更快。     

Motion Smoothing Using Wavelets

Smooth motion generation is an important issue in the computer animation and virtual reality areas. The motion of a rigid body consists of translation and orientation. The former is described by a space curve in 3-dimensional Euclidean space, while the latter is represented by a curve in the unit quaternion space. Although there exist well-known techniques for smoothing the translation data, smoothing the orientation data is yet to be explored due to the nonlinearity of the unit quaternion space. This paper presents a wavelet-based algorithm for smoothing noise-embedded motion data and the experiment shows the effectiveness of the proposed algorithm.     

A SLAM based on auxiliary marginalised particle filter and differential evolution

FastSLAM is a framework for simultaneous localisation and mapping (SLAM) using a Rao-Blackwellised particle filter. In FastSLAM, particle filter is used for the robot pose (position and orientation) estimation, and parametric filter (i.e. EKF and UKF) is used for the feature location's estimation. However, in the long term, FastSLAM is an inconsistent algorithm. In this paper, a new approach to SLAM based on hybrid auxiliary marginalised particle filter and differential evolution (DE) is proposed. In the proposed algorithm, the robot pose is estimated based on auxiliary marginal particle filter that operates directly on the marginal distribution, and hence avoids performing importance sampling on a space of growing dimension. In addition, static map is considered as a set of parameters that are learned using DE. Compared to other algorithms, the proposed algorithm can improve consistency for longer time periods and also, improve the estimation accuracy. Simulations and experimental results indicate that the proposed algorithm is effective.     

列车组合定位中改进CPF算法的探讨

针对在GNSS/INS列车组合定位中普遍采用的扩展卡尔曼滤波(EKF)、无迹卡尔曼滤波(UKF)等滤波技术无法满足复杂的高速列车组合定位环境问题,研究了列车组合定位中改进的容积粒子滤波(CPF)算法,提出了基于改进CPF算法的列车组合定位信息融合技术。该算法采用马尔科夫链蒙特卡洛(MCMC)移动方法来解决粒子退化问题,进而提高滤波性能。使用Matlab对改进算法进行仿真,结果表明改进CPF具有更小的位置误差和速度误差,提高了列车非线性运动过程中的定位精度。     

基于误差状态卡尔曼滤波估计的旋翼无人机输入饱和控制

针对GPS（global positioning system）信号缺失环境下无人机自主飞行控制问题,设计了一种基于视觉与IMU（inertial measurement unit）融合的误差状态卡尔曼滤波（ESKF）框架,并在此基础上提出了一种新的输入饱和控制方法以进一步缓解视野约束以及运动模糊问题．不同于传统的扩展卡尔曼滤波（EKF）框架,本文设计的滤波框架是对误差状态进行更新与校正,而不是直接对系统状态进行估计．由于误差状态是小量,并且其线性程度较高,因此相对于系统状态局部线性化而言,误差状态的局部线性化的模型误差更小,进而可以提高状态估计的精度．基于ESKF框架得到的全状态估计,本文提出了一种新的线性与双曲正切混合的饱和函数,进而设计了输入饱和控制器并通过李亚普诺夫函数证明了闭环系统平衡点的渐近稳定性．最后,在旋翼无人机平台上的对比实验结果表明：本文ESKF方法得到的状态估计精度更高．另外,本文所提出的输入饱和控制方法有助于保证视觉特征在视野之内,并且比有界积分控制方法有更好的暂态以及稳态性能．     

基于CDKF的飞机姿态角估计

针对扩展卡尔曼滤波(Extend Kalman Filter ,EKF)在飞机姿态估计中存在着计算复杂、线性化误差大等缺点,将一种基于Stirling内插公式的非线性滤波算法—中心差分卡尔曼滤波算法(Central Difference Kalman Filter, CDKF)应用于由低精度高噪声传感器组成的低成本飞机姿态估计系统中。首先建立基于四元数的飞机姿态数学模型,然后用CDKF方法进行姿态估计,并通过实测数据进行验证。实验结果表明, CDKF方法不仅有效地提高了飞机姿态估计的精度和稳定性;而且不需要模型的具体解析形式,避免了复杂的Jacobian矩阵的计算,算法更简单,也更容易实现,优于常用的EKF方法。     

四元数卡尔曼滤波组合导航算法性能分析

为分析四元数卡尔曼滤波组合导航算法在飞行器姿态估计中的性能,在建立四元数卡尔曼滤波观测方程、状态方程和方差计算模型的基础上,分别设计了陀螺/加速度计/磁强计组合导航仿真算例和陀螺/加速度计初始对准实验,比较了四元数卡尔曼滤波组合导航算法相较于传统扩展卡尔曼滤波组合导航算法在计算量、收敛性、收敛速度、收敛精度方面的性能.分析结果表明该滤波器无须扩展卡尔曼滤波器的线性化过程,计算量小,算法实现简单;收敛性和收敛速度均优于扩展卡尔曼滤波器.收敛精度较扩展卡尔曼滤波器高出约两个数量级,但收敛过程中存在一个比扩展卡尔曼滤波器精度低的时间区间.