共查询到20条相似文献，搜索用时 15 毫秒
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A non‐smooth optimization technique to directly compute a lower bound on the skew structured singular value ν is developed. As corroborated by several real‐world challenging applications, the proposed technique can provide tighter lower bounds when compared with currently available techniques. Moreover, in many cases, the determined lower bound equals the true value of ν. Thanks to the efficiency of the non‐smooth technique, the algorithm can be applied to problems involving even a significant number of uncertain parameters. Another appealing feature of the proposed non‐smooth approach is that the dimension of repeated scalar uncertainties in the overall structured uncertainty matrix has little impact on the computational time. The technique can be used to compute a lower bound on the structured singular value μ as well. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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This paper considers the application of the skewed structured singular value to the robust stability of systems subject to strictly real parametric uncertainty. Three state‐space formulations that counteract the discontinuous nature of this problem are detailed. It is shown that the calculation of the supremum of the structured singular value over a frequency range using these formulations transforms into a single skewed structured singular value calculation. Similar to the structured singular value, the exact calculation of the skewed structured singular value is an NP‐hard problem. In this work, two efficient algorithms that determine upper and lower bounds on the skewed structured singular value are presented. These algorithms are critically assessed using a series of robustness analysis tests on a safety‐critical experimental drive‐by‐wire vehicle. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Michael K. H. Fan 《Systems & Control Letters》1992,18(6):409-421
The structured singular value (SSV or μ) is known to be an effective tool for assessing robust performance of linear time-invariant models subject to structured uncertainty. Yet all single μ analysis provides is a bound β on the uncertainty under which stability as well as H∞ performance level of κ/β are guaranteed, where κ is preselectable. In this paper, we introduce a related quantity ν which provides answers for the following questions: (i) given β, determine the smallest with the property that, for any uncertainty bounded by β, an H∞ performance level of is guaranteed; (ii) conversely, given , determined the largest β with the property that, again, for any uncertainty bounded by β, an H∞ performance level of is guaranteed. Properties of this quantity are established and approaches to its computation are investigated. Both unstructured uncertainty and structured uncertainty are considered. 相似文献
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This paper presents a systematic robust control framework based on the structured approach to address the synthesis of the atmospheric ascent‐flight control system of a launch vehicle. To introduce this synthesis framework, the control problem is first formulated to recover the classically designed baseline rigid‐body controller of the actual VEGA launcher VV05 mission. This legacy recovery builds the necessary background for a good understanding of the problem and increases confidence for its transfer to the Space industry. Subsequently, it is shown how to systematically augment the robustness of the design from the synthesis stage against wind turbulence perturbations and parametric uncertainty. The resulting controller is verified via classical stability margins and robust structured singular value analyses and finally validated using nonlinear, time‐domain simulations in a Monte Carlo campaign. It is highlighted that this robust synthesis framework allows to obtain a controller with improved robust stability and global performance, and more importantly, it provides a more systematic methodology for design. 相似文献
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Exploitation of the NP hard, mixed μ problem structure provides a polynomial time algorithm that approximates μ with usually reasonable answers. When the problem is extended to the skew μ problem, an extension of the existing method to the skew μ formulation is required. The focus of this paper is to extend the μ upper bound derivation to the skew μ upper bound and show its direct computation by way of an Osborne balancing algorithm and an linear matrix inequality (LMI) algorithm. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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In this article, a complete modelling, synthesis, and analysis methodology of control compensators for descent and landing (D&L) on small planetary bodies is presented. These missions are scientifically very rewarding but technically extremely challenging due to the complex and poorly known environment around those bodies, which calls for the ability to manage competing robustness and performance requirements. While this issue is typically addressed via the redefinition of D&L guidance strategies, here, it is tackled through the augmentation with a simple yet robust control compensator. This compensator is designed using linear fractional transformation modelling to capture the interplay with uncertain gravity fields and the recently developed structured optimisation framework, which has been proved particularly suitable for industry‐oriented applications. The proposed approach is completely generic but uses the scenario of a landing on the Martian moon Phobos as an illustrative example. Different compensators are then verified and compared analytically via the structured singular value μ and through high‐fidelity Monte Carlo simulation. 相似文献
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In this paper we study stability radii of positive linear discrete-time systems under affine parameter perturbations. It is shown that real and complex stability radii of positive systems coincide for arbitrary perturbation structures, in particular, for blockdiagonal disturbances as considered in μ-analysis. Estimates and computable formulae are derived for these stability radii. The results are derived for arbitrary perturbation norms induced by monotonic vector norms (e.g. p-norms, 1⩽p⩽∞). © 1998 John Wiley & Sons, Ltd. 相似文献
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The structured singular value (s.s.v)μ enables the study of robust stability and performance of a controller in the presence of real parametric uncertainties and complex uncertainties corresponding to neglected dynamics. In spite of the NP-hard characteristic of the problem, it is now possible to compute an interval for the s.s.v. μ using polynomial-time algorithms. The skewed s.s.v. ν was introduced by Fan and Tits in the context of robust performance analysis. The primary aim of this paper is to propose a new mixed ν upper bound, which is applicable to problems with a special, but practically important, structure. We then illustrate through a realistic missile example that certain problems naturally require the ν tool rather than the μ tool. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
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The computation of the general structural singular value (μ) is NP hard, so quick solutions to medium sized problems must often be approximate. In many of the cases where the current approximate methods are unsatisfactory, improved solutions are highly desirable. It is shown that, despite their worst-case combinatorial nature, branch and bound techniques can give substantially improved solutions with only moderate computational cost. © 1997 by John Wiley & Sons, Ltd. 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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本文研究的问题如下,对于具有构造型不确定性的被控对象,设计一动态反馈控制器,使得闭环系统满足Ｈ∞鲁棒次优性能要求。同时,对于满足给定微分方程的参考输入信号,具有鲁棒调节性能。研究结果表明,通过解一适当的Ｈ∞标准设计问题可以得到理想的控制器。基于黎卡提不等式的正定解,给出了控制器的具体设计方法。最后,还给出了该设计方法在二自由度机械手上应用的实验结果。 相似文献
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Javad Ahmadi Ali Khaki-Sedigh Abdolreza Ohadi 《International journal of control》2013,86(9):1380-1400
In this article, a new methodology for robust actuator weighting in the control allocation (CA) problem of input redundant feedback systems is addressed. The methodology is based on the control structural properties of the plant which were previously used for control configuration selection. Robust performance (RP) measures including H ∞ norm and structured singular value of the closed-loop system are used in this article. The capability of the approach is proven with application to lateral dynamics control of the vehicle over-actuated with front and rear steering systems. Employing the RP measures, it is concluded that the vehicle feedback control with front steering angles gives superior RP properties in comparison with the feedback loop of the rear steering angles. Based on these results, the penalty weightings in the cost function of the CA unit are determined. Simulation results based on nonlinear seven degrees of freedom vehicle handling model show that the selection of penalty weightings in the CA unit based on the RP properties of the control inputs (front and rear steering angles) improves the RP of the closed-loop. 相似文献
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In this paper, we consider the problems of synthesizing PID controllers for robust stability and performance for a given linear time‐invariant plant subject to both parametric and H∞‐norm‐bounded perturbations. Using results from the area of parametric robust control, synthesis problems are converted into simultaneous stabilization of a family of complex segment polynomials. The results on H∞ PID synthesis are then used to devise a design procedure for determining the admissible PID gain values. One of the important features of the proposed method is that it constructively characterizes the approximated set of all admissible PID controllers. This characterization can facilitate the optimal design of any additional design requirements. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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In this paper, a robust controller design method is first formulated to deal with both performance and robust stability specifications for multivariable processes. The optimum problem is then dealt with using a loop‐shaping H∞ approach, which gives a sub‐optimal solution. Then a PID approximation method is proposed to reduce a high‐order controller. The whole procedure involves selecting several parameters and the computation is simple, so it serves as a PID tuning method for multivariable processes. Examples show that the method is easy to use and the resulting PID settings have good time‐domain performance and robustness. 相似文献