排序方式: 共有15条查询结果,搜索用时 312 毫秒
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提出了一种可用于色噪声背景的基于子空间的改进半盲信道估计算法。根据正交频分复用(OFDM)系统模型,利用所获色噪声背景的噪声向量与信道冲激响应矩阵的正交性估计信道冲激响应,给出了算法的步骤。仿真结果表明:算法有较好的收敛性和稳定性。 相似文献
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Recently, flutter active control using linear parameter varying (LPV) framework has attracted a lot of attention. LPV control synthesis usually generates controllers that are at least of the same order as the aeroelastic models. Therefore, the reduced-order model is required by syn-thesis for avoidance of large computation cost and high-order controller. This paper proposes a new procedure for generation of accurate reduced-order linear time-invariant (LTI) models by using sys-tem identification from flutter testing data. The proposed approach is in two steps. The well-known poly-reference least squares complex frequency (p-LSCF) algorithm is firstly employed for modal parameter identification from frequency response measurement. After parameter identification, the dominant physical modes are determined by clear stabilization diagrams and clustering tech-nique. In the second step, with prior knowledge of physical poles, the improved frequency-domain maximum likelihood (ML) estimator is presented for building accurate reduced-order model. Before ML estimation, an improved subspace identification considering the poles constraint is also proposed for initializing the iterative procedure. Finally, the performance of the proposed procedure is validated by real flight flutter test data. 相似文献
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Due to limitations to extract invariant features for recognition when the aircraft presents various poses and lacks enough samples for training, a novel algorithm called Weighted Marginal Fisher Analysis with Spatially Smooth (WMFA-SS) for extracting invariant features in aircraft rec- ognition is proposed. According to the Graph Embedding (GE) framework, Heat Kernel function is firstly introduced to characterize the interclass separability when choosing the weights of penalty graph. Furthermore, Laplacian penalty is applied to constraining the coefficients to be spatially smooth in this algorithm. Laplacian penalty is able to incorporate the prior information that neigh- boring pixels are correlated. Besides, using a Laplacian penalty can also avoid the singularity of Laplacian matrix of intrinsic graph. Once compact representations of the images are obtained, it can be considered as invariant features and then be performed in classification to recognize different patterns of aircraft. Real aircraft recognition experiments show the superiority of our proposed WMFA-SS in comparison to other GE algorithms and the current aircraft recognition algorithm; the accuracy rate of our proposed method is 90.00% for dataset BH-AIR1.0 and 99.25% for dataset BH-AIR2.0. 相似文献
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为了解决过程噪声和测量噪声为高斯有色噪声且反馈控制器未知情况下的闭环系统辨识问题,给出了基于子空间辨识框架下的闭环辨识算法。算法通过选择适当的辅助变量,构造出噪声过程的高阶累积量,并利用高阶累积量对高斯噪声不敏感的特性来抑制噪声的影响,最后再使用子空间算法辨识系统的状态空间模型。数值仿真表明,对于存在高斯有色噪声的闭环系统,该辨识算法可以得到无偏的系统状态空间模型。 相似文献
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Identification of the state-space model and payload mass parameter of a flexible space manipulator using a recursive subspace tracking method 总被引:1,自引:0,他引:1
The on-orbit parameter identification of a space structure can be used for the modification of a system dynamics model and controller coefficients. This study focuses on the estimation of a system state-space model for a two-link space manipulator in the procedure of capturing an unknown object, and a recursive tracking approach based on the recursive predictor-based subspace identification (RPBSID) algorithm is proposed to identify the manipulator payload mass parameter. Structural rigid motion and elastic vibration are separated, and the dynamics model of the space manipulator is linearized at an arbitrary working point (i.e., a certain manipulator configuration). The state-space model is determined by using the RPBSID algorithm and matrix transformation. In addition, utilizing the identified system state-space model, the manipulator payload mass parameter is estimated by extracting the corresponding block matrix. In numerical simulations, the presented parameter identification method is implemented and compared with the classical algebraic algorithm and the recursive least squares method for different payload masses and manipulator configurations. Numerical results illustrate that the system state-space model and payload mass parameter of the two-link flexible space manipulator are effectively identified by the recursive subspace tracking method. 相似文献
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Estimating cross-range velocity is a challenging task for space-borne synthetic aperture radar(SAR), which is important for ground moving target indication(GMTI). Because the velocity of a target is very small compared with that of the satellite, it is difficult to correctly estimate it using a conventional monostatic platform algorithm. To overcome this problem, a novel method employing multistatic SAR is presented in this letter. The proposed hybrid method, which is based on an extended space-time model(ESTIM) of the azimuth signal, has two steps: first, a set of finite impulse response(FIR) filter banks based on a fractional Fourier transform(FrFT) is used to separate multiple targets within a range gate; second, a cross-correlation spectrum weighted subspace fitting(CSWSF) algorithm is applied to each of the separated signals in order to estimate their respective parameters. As verified through computer simulation with the constellations of Cartwheel, Pendulum and Helix, this proposed time-frequency-subspace method effectively improves the estimation precision of the cross-range velocities of multiple targets. 相似文献