共查询到19条相似文献,搜索用时 187 毫秒
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本文在简要介绍H^∞控制的基础上,提出了应用H^∞控制中混合灵敏度法设计伺服系统的方法。这种方法以系统传递函数的H^∞范数作为性能指标,同时谋求最小的灵敏度函数价值和最小的补灵敏度函数值,从而实现具有鲁棒跟踪特性和鲁棒稳定性的伺服系统。 相似文献
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提出了一种具有阶次限制的鲁棒控制器设计方法, 该算法将控制系统的性能指标转化为灵敏度函数问题, 并利用Nevanlinna-Pick插值算法进行求解. 提出了一种改进的同伦算法, 将其用于求解由灵敏度函数产生的非线性方程. 基于改进同伦算法设计的鲁棒控制器 不仅避免了传统H∞控制中加权函数的选择问题, 而且克服了鲁棒控制器阶次较高的缺陷. 最后,文章以4阶系统为例, 设计了具有阶次限制的H∞鲁棒控制器, 通过与传统鲁棒控制器的比较可以看出, 基于本文方法设计的控制器不仅具有较低的阶次, 而且其控制性能也具有明显的优越性. 相似文献
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1引言Doyle在1982年提出的结构奇异值(μ)方法是分析和综合结构式不确定系统的有力工具[1,2].基于结构奇异值分析的小μ定理[2]给出了具有多个摄动块的线性动态系统鲁棒稳定的充要条件.而鲁棒性能定理[2]则进一步地将鲁棒稳定性问题和鲁棒性能问题统一成μ分析问题.然而.我们注意到,在所有研究结构奇异值的文献中,均要求块对角摄动矩阵中每个子摄动块是方的.这一要求无疑大大限制了μ方法的应用,因为非方摄动块在系统中是经常存在的.此时对Doyle给出的结构奇异值的上界函数[1]必须进行修正.2非方… 相似文献
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段镇 《计算机测量与控制》2015,23(8):2713-2715
为抑制无人机飞行模态切换时舵面跳变使机体产生的大过载,降低无人机对舵系统及结构可用过载的要求,将鲁棒伺服LQR方法与经典控制方法相结合设计了飞行控制律;以俯仰角控制模态为例,对鲁棒伺服LQR控制方法的特性进行了分析,俯仰角速率回路采用鲁棒伺服LQR最优控制方法设计了控制律,俯仰角回路采用经典控制方法设计了控制律,并通过非线性数字仿真对控制律的控制效果进行了验证;仿真结果表明:鲁棒伺服LQR控制比常规PID控制超调量减小50%,且大大减小了响应初期的升降舵偏角突变,降低了对机体可用过载的要求;该控制律形式简单,易于工程实现。 相似文献
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Xiaodong Liu Yunjie Wu Yu Zhang Song Xiao 《International Journal of Control, Automation and Systems》2014,12(2):302-308
Linear quadratic regulator (LQR) is an optimal controller being used for linear systems, and it can minimize the comprehensive quadratic performance index (QPI) with respect to convergence error and control consumption. However, LQR lacks the robust property to cope with parameter perturbations and external disturbances. Aiming at the above deficiency of LQR, a robust LQR (RLQR) is proposed for linear systems under the guideline of planes cluster approaching mode (PCAM). In the proposed RLQR, one nonlinear item is introduced into control law, and it cooperates with the other linear item to guarantee the global asymptotic stability in the presence of equivalent disturbances. The conditions of global asymptotic stability are deduced by the method of Lyapunov function. Simulation results present that, the chosen LTI plant using RLQR possesses smaller QPI in the existence of timevarying disturbances, compared with the conventional LQR and sliding mode controller (SMC). 相似文献
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The authors consider the robust performance problem of maintaining a small output sensitivity function despite the presence of block diagonal uncertainty at the plant input. For the case of two blocks of uncertainty, they study this problem by analyzing bounds on the structured singular value. It is shown that the potential difficulty of attaining robust performance is primarily determined by the difficulty of maintaining a small set of interaction parameters. The authors derive a robustness indicator which is useful in detecting this potential difficulty. The indicator is a function of both the plant condition number and its input directionality properties 相似文献
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针对两种常见的信号奇异点:脉冲型奇异点和阶跃型奇异点,证明信号的奇异点与信号小波变换的最值有关,如果适当选择小波基函数,那么信号的脉冲奇异点将对应于小波基函数的最值点,而信号的阶跃奇异点将对应于小波基函数的原函数的最值点。据此,设计了一个新的基于小波变换的信号奇异点分步检测法(Hierarchical Singular Point Detection based on Wavelet Transform,HSPDWT),该方法的特点是根据脉冲奇异点和阶跃奇异点的不同特征分两步从信号中提取奇异点。仿真及真实信号上的实验证明了HSPDWT的可行性和有效性。 相似文献
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YASUAKI OISHI 《International journal of control》2013,86(5):1085-1104
A new expression of a non-conservative robust stability condition is derived for sampled-data systems taking into consideration its convenience in numerical computation. Our expression is described using a global maximum of a certain differentiable function, while the conventional expression includes a global maximum of a structured singular value, which is expensive to compute. When the sampling period is long, the advantages of our expression become clear. A possible problem is that the maximized function may be multimodal. However, the conventional expression has the same problem and even a local maximum is shown to give useful information. Our expression is applicable to a fairly large class of systems including the multi-input multi-output additive and multiplicative perturbation models. Using an example, we show how our expression is computed and make a comparison with the conventional expression. 相似文献
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We investigate the generalized linear quadratic regulator (LQR) control where the dimension of the control input is strictly greater than the dimension of the controlled output, and the weighting matrix on the control signal is singular. The dual problem is the generalized Kalman filtering where the dimension of the input noise process is strictly smaller than the dimension of the output measurement, and the covariance of the observation noise is singular. These two problems are intimately related to inner-outer factorizations for nonsquare stable transfer matrices with square inners of the smaller size. Such inner-outer factorizations are in turn related to spectral factorizations for power spectral density (PSD) matrices whose normal ranks are not full. We propose iterative algorithms and establish their convergence for inner-outer and spectral factorizations, which in turn solve the generalized LQR control and Kalman filtering. 相似文献
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分式过程神经元网络在网络流量预测中的应用 总被引:1,自引:0,他引:1
为更好解决网络流量预测问题,依据函数逼近论中分式的函数逼近性质和拟合能力要远远大于线性函数的性质,以及过程神经元网络对时变函数的非线性变换能力,提出一种分式过程神经元网络模型及其学习算法。实验结果证明,该网络模型对具有奇异值过程函数的柔韧逼近性质和在奇异值点附近区域反应的灵敏性优于一般过程神经元网络,以网络实测数据对模型进行训练和流量预测,取得了较好的应用效果。 相似文献
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ISOMAP是一种经典的非线性降维方法,能够有效地发现高维非线性数据集的低维几何结构,但该算法对奇异值和噪声非常敏感。利用具有鲁棒性的主成分分析(Robust PCA)来探测奇异点,并对奇异点进行适当处理以降低ISOMAP对其的敏感程度。所提出的算法直观且易于理解,实验结果也证明它具有较好的鲁棒性,而且在奇异点较多的情况下仍能保持数据的整体结构。 相似文献
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为了更好的表现自然图像的曲线特性,进一步提高数字水印算法的鲁棒性,提出一种基于Curvelet-DSVD和视觉密码相结合的强鲁棒零水印算法。首先对原始图像进行Arnold置乱;其次进行Curvelet变换得到低频域信息,对低频域信息进行分块并对各个块进行双奇异值分解(DSVD),利用块最大奇异值与整体奇异值均值之间的关系构造特征矩阵,同时利用视觉密码将水印信息生成两个共享份;最后将其中一个共享份进行Arnold置乱后与特征矩阵进行异或运算生成零水印。实验结果表明,该算法能够有效地抵抗常规攻击,与现有的零水印算法相比,鲁棒性更强,安全性更高。 相似文献
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《Expert systems with applications》2014,41(17):7858-7867
This paper presents an optimized watermarking scheme based on the discrete wavelet transform (DWT) and singular value decomposition (SVD). The singular values of a binary watermark are embedded in singular values of the LL3 sub-band coefficients of the host image by making use of multiple scaling factors (MSFs). The MSFs are optimized using a newly proposed Firefly Algorithm having an objective function which is a linear combination of imperceptibility and robustness. The PSNR values indicate that the visual quality of the signed and attacked images is good. The embedding algorithm is robust against common image processing operations. It is concluded that the embedding and extraction of the proposed algorithm is well optimized, robust and show an improvement over other similar reported methods. 相似文献