共查询到20条相似文献,搜索用时 31 毫秒
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Gerasimos G. Rigatos 《Robotics and Autonomous Systems》2012,60(7):978-995
The paper studies and compares nonlinear Kalman Filtering methods and Particle Filtering methods for estimating the state vector of Unmanned Aerial Vehicles (UAVs) through the fusion of sensor measurements. Next, the paper proposes the use of the estimated state vector in a control loop for autonomous navigation and trajectory tracking by the UAVs. The proposed nonlinear controller is derived according to the flatness-based control theory. The estimation of the UAV’s state vector is carried out with the use of (i) Extended Kalman Filtering (EKF), (ii) Sigma-Point Kalman Filtering (SPKF), (iii) Particle Filtering (PF), and (iv) a new nonlinear estimation method which is the Derivative-free nonlinear Kalman Filtering (DKF). The performance of the nonlinear control loop which is based on these nonlinear state estimation methods is evaluated through simulation tests. Comparing the aforementioned filtering methods in terms of estimation accuracy and computation speed, it is shown that the Sigma-Point Kalman Filtering is a reliable and computationally efficient approach to state estimation-based control, while Particle Filtering is well-suited to accommodate non-Gaussian measurements. Moreover, it is shown that the Derivative-free nonlinear Kalman Filter is faster than the rest of the nonlinear filters while also succeeding accurate, in terms of variance, state estimates. 相似文献
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Wei-Der Chang 《Digital Signal Processing》2009,19(4):693-699
This paper presents a novel secure communication system for digital signal transmissions. It contains four important parts: modulation, chaotic transmitter, chaotic receiver, and demodulation. The modulation mechanism is to modulate each of delivered bit information to be a carrier signal in the continuous form. Then this carrier signal is taken as a parameter of the chaotic system, called the unified chaotic system. Such a system possesses three different types of chaos characterizations depending on its system's parameter, and this guarantees the communication security more. In the public channel, only three chaotic state variables are delivered and this means that the important carrier information is efficiently screened. According to chaotic states received in the receiver terminal, the continuous carrier signal is decrypted using certain adaptation mechanisms. Finally, the proposed demodulation method can successfully recover the original bit information which is embedded in the communication systems. Some simulation results are provided to verify the efficiency of the proposed secure communication system. 相似文献
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CDMA系统信道时间延迟估计是一个非线性的迭代过程。UKF算法能够避免EKF由于线性化非线性系统而带来的误差过大等问题,比EKF估计的更加精确。利用UKF算法对CDMA系统信道的幅度衰减参数与延时参数进行了估计。在研究中考虑到了多址干扰和远近效应对信道参数的影响,仿真结果表明UKF算法能有效地抑制远近效应及多址干扰,估计出无线信道参数。 相似文献
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MIMO技术在不增加信号带宽和发射功率的情况下,通过在发送端和接收端分别使用多个发送天线和接收天线来抑制信道衰落和噪声。利用MIMO技术的优势,设计了一种基于差分混沌键控(DCSK)的MIMO-DCSK混沌通信方案。针对这一方案,通过进一步的数学推导,得到系统在高斯信道下的理论误码率公式,并在MATLAB环境中进行了仿真验证。理论分析和仿真结果表明:在相同的信噪比条件下,MIMO-DCSK混沌通信系统的误码率比传统DCSK通信系统要小得多。因此,MIMO-DCSK混沌通信方案能够有效改善混沌通信系统的误码性能。 相似文献
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Moussa Yahia Pascal Acco Malek Benslama 《International Journal of Control, Automation and Systems》2011,9(6):1021-1027
This paper proposes to decompose the nonlinear dynamic of a chaotic system with Chebyshev polynomials to improve performances
of its estimator. More widely than synchronization of chaotic systems, this algorithm is compared to other nonlinear stochastic
estimator such as Extended Kalman Filter (EKF) and Unscented Kalman Filter (UKF). Chebyshev polynomials orthogonality properties
is used to fit a polynomial to a nonlinear function. This polynomial is then used in an Exact Polynomial Kalman Filter (ExPKF)
to run real time state estimation. The ExPKF offers mean square error optimality because it can estimate exact statistics
of transformed variables through the polynomial function. Analytical expressions of those statistics are derived so as to
lower ExPKF algorithm computation complexity and allow real time applications. Simulations under the Additive White Gaussian
Noise (AWGN) hypothesis, show relevant performances of this algorithm compared to classical nonlinear estimators. 相似文献
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提出了一种新型的图像保密通信技术。利用混沌序列对初值敏感性、伪随机性等特点,在发送端,将图像信息首先经过常规加密技术DES加密,然后再经过混沌序列进行二次加密。接收端对收到的信号进行相应的图像解密,恢复出原始图像。这样,可实现对图像的DES与混沌序列的级联加密,发挥它们各自的优点,使图像保密通信的安全性得到提高。计算机仿真结果表明该方案的有效性。 相似文献
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现有的差分混沌移位键控(DCSK)通信系统主要的缺陷是传输速率较低,为此提出了一种无信号间干扰的相关延迟-差分混沌移位键控(CD-DCSK)通信方案。在发送端,由正交信号发生器产生两路正交混沌信号,并经符号函数归一化以保持发送信号的能量恒定,然后,这两路混沌信号与其延迟不同时间间隔后的混沌信号分别调制1 bit数据信息形成一帧发送信号。在解调端,采用相关解调提取数据信息,通过检测相关器输出结果的符号恢复信息比特。利用高斯近似(GA)法分析了系统在加性高斯白噪声(AWGN)信道下的理论误码率(BER)性能,并与经典的混沌通信系统进行了比较。分析及实验结果表明:与DCSK系统相比,无信号间干扰的CD-DCSK系统的传输速率提升了50个百分点,且其误码性能优于相关延迟移位键控(CDSK)系统。 相似文献
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由于分数阶混沌动力学系统比整数阶系统具有更复杂的动力学特性,且能为图像加密方案提供更多的自由度,基于分数阶陈氏混沌系统,提出了一种图像加密方法。在发送端,驱动系统产生混沌信号,利用混沌信号扰乱明文图像的像素位置,将扰乱后的图像掩盖在混沌信号中,得到传输的密文图像。在接收端,通过同步系统去掩盖,进行像素位置扰乱的逆操作,恢复明文图像。最后对提出的加密算法进行了安全性分析。实验结果表明,该加密算法安全性高,具有良好的研究价值和应用前景 相似文献
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针对统一混沌系统和Qi混沌系统的模型,根据主动控制思想和Lyapunov稳定性定理,构造主动控制器使得这两个异结构的混沌系统实现同步,并且实现了驱动系统参数已知而响应系统参数未知的异结构混沌系统的白适应同步,并且能较怏的辨析出系统的未知参数.并利用MATLAB进行数字仿真,将同步的异结构混沌系统应用到混沌掩盖和混沌扩频保密通信中.仿真结果表明,异结构混沌系统能够实现稳定的同步,且在混沌掩盖和混沌扩频保密通信中,有用信号均能有效地在接收端恢复出来. 相似文献
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This paper proposes a new digital communication scheme,which uses chaotic signals based on the adaptive synchronization and parameter identification technique of chaotic systems reported recently.Due to the multi signal character,this scheme combines the chaotic signal transmission with the MIMO channel technique in a wireless environment,which is different from the traditional chaotic communication frameworks.From a practical perspective,an outline of modulation,channel model,demodulation and non-coherent detection is investigated.Furthermore,system performance is evaluated by simulations,and improvements on this scheme are also discussed. 相似文献
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针对传统全球定位系统(GPS)接收机在高动态环境下跟踪性能不理想,提出一种基于载波频率辅助相位的GPS信号跟踪算法。利用锁频环(FLL)辅助锁相环(PLL)的方式代替传统单一跟踪环路,通过卡尔曼(Kalman)滤波器对接收机各跟踪通道中频信号进行综合处理。根据多条跟踪通道的伪距和伪距率残差对系统状态参量进行综合估计,并搭建Kalman滤波器的状态方程和量测方程,给出了跟踪环路反馈量,与传统标量跟踪模式下的跟踪性能进行了对比。仿真结果表明,基于载波频率辅助相位的GPS信号跟踪算法进入稳态时间减小了100 ms,位置误差精度提高了5 m,速度误差精度提高了近3 m/s,在接收机用户快速运动的环境下,能够很好地处理高动态信号。 相似文献
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针对一类具有不确定参数的非线性混沌系统,本文提出了一种新的混沌通信同步方法。考虑混沌通信的特点,通过合理的假设,该类系统可以作为一类在接收端或可观测输出端由附加白噪声驱动的线性时变系统。然后,同步问题通过最优滤波的方法来解决,可以应用Kalman滤波的结论进行估计。在一些充分条件下,响应系统的状态能够渐进跟踪驱动系统的状态,并且在输出端包含干扰噪声的情况下,仍能保证良好的跟踪轨迹。 相似文献
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Genesio混沌系统的广义同步控制 总被引:1,自引:0,他引:1
本文基于Genesio 混沌系统提出了一种广义同步系统设计方案. 首先, 利用标量输
出信号对发射系统进行迭代变换; 然后利用变换后的系统构造响应系统. 最后, 将该同步系
统应用到保密通讯中. 而且, Hurwitz 稳定性理论保证了广义同步系统的稳定性. 数值仿真
结果表明: 尽管发射系统与响应系统具有不同的结构, 但是它们不仅能够达到广义同步, 而
且信息信号能够精确复现. 相似文献
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本文将非线性控制系统的输入-输出线性化方法应用于混沌系统的同步中。首先对发送系统和接收系统进行适当的坐标变换,分别得到一个具有规范型或类规范型的新系统,再对两个新系统进行比较得到误差系统.然后通过对误差系统进行反馈变换,从而实现混沌系统的输出及其导数的同步.当满足一定条件.还可实现所有状念变量的同步.此方法所需的发送信号仅为标量信号,适于保密通信。对Lorenz系统、Rossler系统的仿真证明了该方法的有效性。 相似文献
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虽然无先导卡尔曼滤波(UKF)技术在性能上要优于一阶线性化的扩展卡尔曼滤波(EKF)技术,但是对于改进型Logistic混沌映射的扩频通信系统,UKF运算时间长,算法复杂。针对上述缺点以及改进型Logistic映射的泰勒展开式最高项为二阶的特点,提出将二阶EKF运用到接收系统中,该接收系统能精确到泰勒展开式的二阶,达到与UKF相同的性能。相比UKF的复杂算法更加简单,运算速度也更快。仿真实验表明,虽然二阶EKF与UKF的误码率相同,但在运算速度与复杂度方面均优于UKF。 相似文献