共查询到18条相似文献,搜索用时 93 毫秒
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反馈系统的设计会受到闭环系统特性的制约. 本文给出了反馈控制系统接近虚轴或虚轴上的稳定零点对跟踪误差的时间域积分约束. 这一时间域积分约束是任何一个线性时不变系统为保证其闭环系统的稳定性, 其跟踪误差必须满足的. 接近虚轴或虚轴上的稳定零的存在表明跟踪误差与调节时间之间存在某种折中. 对固定的调节时间, 本文给出了在虚轴上存在零点情形下, 其跟踪误差的无穷范数下界的一个有效估计. 此估计表明, 零点的绝对值越小, 其无穷范数的下界越大. 这些约束由一个例子加以解释. 相似文献
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利用新近发展起来的积分二次约束(IQC)方法,对离散时间系统,给出了其鲁棒稳定性分析准则,使一大类古典稳定性结果可以统一和概括在积分二次约束的框架之下。并且,利用积分二次约束方法,讨论了一类混合摄动系统的鲁棒稳定性。 相似文献
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研究了离散情形下的反馈系统的稳定性问题,利用新近发展起来的积分二次约束(IQC)方法,对离散系统的反馈连接问题,给出了其稳定性分析准则和一些必要条件,这些结果适用于时不变与时变系统.其次,利用已有的结果.得到了离散时变系统MIMO情况下的绝对稳定性问题的一个判据.最后,利用一个较强的IQC定义,给出了判断某一类反馈系统稳定的充分必要条件. 相似文献
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针对输出受不对称时变约束的不确定高阶严反馈系统, 提出一种基于全驱系统方法的高阶自适应动态面输出约束控制方法. 所研究的高阶严反馈系统, 每个子系统都是高阶形式, 通过非线性转换函数将原输出约束系统转换为新的无约束系统, 从而将原系统输出约束问题转化为新系统输出有界的问题. 进一步结合全驱系统方法和自适应动态面控制, 直接将每个高阶子系统作为一个整体进行控制器设计, 而不需要将其转化为一阶系统形式, 有效简化了设计步骤; 同时通过引入一系列低通滤波器来获得虚拟控制律的高阶导数, 以代替复杂的微分运算. 基于Lyapunov稳定性理论证明闭环系统所有信号是一致最终有界的, 系统输出在满足约束的条件下能有效跟踪期望的参考信号, 且可通过调整参数使得系统跟踪误差收敛到零附近的足够小的邻域内. 最后, 通过对柔性关节机械臂系统进行仿真, 验证了所提出控制方法的有效性. 相似文献
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基于生成式的零样本识别方法在生成特征时受冗余信息和域偏移的影响,识别精度不佳.针对此问题,文中提出基于去冗余特征和语义关系约束的零样本属性识别方法.首先,将视觉特征映射到一个新的特征空间,通过互相关信息对视觉特征进行去冗余处理,在去除冗余视觉特征的同时保留类别的相关性,由于在识别过程中减少冗余信息的干扰,从而提高零样本识别的精度.然后,利用可见类和不可见类之间的语义关系建立知识迁移模型,并引入语义关系约束损失,约束知识迁移的过程,使生成器生成的视觉特征更能反映可见类和不可见类之间语义关系,缓解两者之间的域偏移问题.最后,引入循环一致性结构,使生成的伪特征更接近真实特征.在数据集上的实验证实文中方法提高零样本识别任务的精度,并具有较优的泛化性能. 相似文献
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Farshad Merrikh-Bayat 《Journal of Process Control》2013,23(6):817-825
As a very well-known classical fact, non-minimum phase zeros of the process put some limitations on the performance of the feedback system. The source of these limitations is that non-minimum phase zeros cannot be cancelled by unstable poles of the controller since such a cancellation leads to internal instability. The aim of this paper is to propose a method for fractional-order cancellation of non-minimum phase zeros of the process and studying its properties. It is specially shown that the proposed cancellation strategy increases the phase and gain margin without leading to internal instability. Since the systems with higher gain and phase margin are easier to control, the proposed method can be used to arrive at more effective controls, which is also verified by the simulation results. 相似文献
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In this work, we propose a dynamic output feedback robust model predictive control (RMPC) design method for linear uncertain systems with input constraints. In order to handle the input constraints, the control signals are permitted to saturate, which can fully utilize the capability of actuators and thus can reduce the conservatism. For the unavailable states, an ellipsoidal set is used to obtain an estimation, and it is updated at every time instant. A modified RMPC design requirement is used to ensure the recursive feasibility of the optimization problem. Then, the design method is formulated in terms of a convex optimization problem with linear matrix inequality constraints. The proposed output feedback RMPC design method is expected to further reduce the conservativeness. The improvements of the proposed algorithm over the other existing techniques is demonstrated by an example. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Motivated by a robust disturbance rejection problem, in which disturbances are described by an uncertain filter at the plant input, a convex solution is presented for the robust output feedback controller synthesis problem for a particularly structured plant. The uncertainties are characterized by an integral quadratic constraint (IQC) with general frequency‐dependent multipliers. By exploiting the structure of the generalized plant, linear matrix inequality (LMI)‐synthesis conditions are derived in order to guarantee a specified ??2‐gain or ??2‐norm performance level, provided that the IQC multipliers are described by LMI constraints. Moreover, it is shown that part of the controller variables can be eliminated. Finally, the rejection of non‐stationary sinusoidal disturbance signals is considered. In a numerical example, it is shown that specifying a bound on the rate‐of‐variation of the time‐varying frequency can improve the performance if compared with the static IQC multipliers. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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数字助听器系统中的回声消除方法 总被引:1,自引:0,他引:1
提出一种数字助听器回声消除方法,该方法通过引进预滤波单元,解决了由于前向路径存在而导致数字助听器系统受话器输出信号与麦克风输入信号存在相关性的问题,进而保证了对回声路径的自适应估计算法收敛于无偏估计。提出了数字助听器回声路径估计的自适应次梯度投影算法,相比传统的NLMS自适应算法收敛速度更快,收敛精度更高,对噪声鲁棒性强。使用白噪声和真实语音信号的仿真实验证明:对于长的房间回声路径或短的助听器回声路径,该算法都能快速准确地收敛到正确路径。 相似文献
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嵌入式系统的节能问题是系统设计中的热点。在保证系统整体控制性能的前提下达到尽可能低的能耗,一直是嵌入式控制系统中能量管理的目标。由于诸多不确定性因素和负载的动态变化,嵌入式系统总是运行在不可预期的开放环境中。为了有效处理CPU负载变化及控制任务执行时间不确定等问题,提出了一种基于模糊逻辑的能量觉察反馈调度方法。反馈调度器动态调节CPU的处理速度,实现对CPU利用率的有效控制,从而提供了一种有效的能量管理机制。通过仿真实验与常规动态电压调整方法、传统方法以及理想情况进行比较,验证了该反馈调度方法的有效性。 相似文献
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In this paper, an L1 adaptive output‐feedback controller is developed for multivariable nonlinear systems subject to constraints using online optimization. In the L1 adaptive architecture, an adaptive law will update the adaptive parameters that represent the nonlinear uncertainties such that the estimation error between the predicted state and the real state is driven to zero at every integration time step. Of course, neglection of the unknowns for solving the error dynamic equations will introduce an estimation error in the adaptive parameters. The magnitude of this error can be lessened by choosing a proper sampling time step. A control law is designed to compensate the nonlinear uncertainties and deliver a good tracking performance with guaranteed robustness. Model predictive control is introduced to solve a receding horizon optimization problem with various constraints maintained. Numerical examples are given to illustrate the design procedures, and the simulation results demonstrate the availability and feasibility of the developed framework. 相似文献