DC-DC buck变换器的混沌控制

基于DC-DC buck变换器电路,采用了一种新的混沌控制方法,即对混沌动力系统增加 一个具有分段二次函数x|x|形式的非线性反馈控制器,使该系统成功地控制到稳定的 周期轨道。数值仿真表明,该控制方法易于实现、控制代价小、结构简单。     

混沌系统的非线性反馈跟踪控制

提出了一种非线性反馈跟踪控制方法,使受控混沌系统既能稳定到相空间的某一个点,也能跟踪某一确定的运动规律.理论分析和实验均表明该控制方法具有极强的鲁棒性. 关键词： 混沌 非线性反馈 跟踪控制 鲁棒性     

利用凹槽滤波引导混沌系统到周期解

通过对混沌动力系统增加一个线性的反馈控制器——凹槽滤波器,引导一大类系统从混沌运动转化为期望的低周期运动.基于混沌的微扰判据——Melnikov方法,解释了该方法实现混沌控制的数学物理机理.控制仿真结果表明,该方法简单而实用,具有良好的应用前景,并能控制超混沌系统 关键词： 混沌控制 凹槽滤波 Melnikov方法     

基于线性状态反馈的混沌系统全局控制

针对一类混沌系统,通过分析其非线性向量场的结构特征,提出了一种全局快速控制混沌的新方法.利用线性状态反馈,分离出一个稳定的独立状态变量方程,使受控的混沌系统逐渐退化为稳定的线性系统,进而完全消除非线性抖振现象.此方法可应用到Lorenz系统族或具有类似结构的新混沌系统的控制中,相应设计出一种结构简单的控制器,保证闭环系统在原点全局渐近稳定.数值算例验证了所提出方法的快捷性和正确有效性. 关键词： 混沌系统 线性状态反馈 全局稳定     

Chen系统的自适应追踪控制

利用非线性单输入控制器实现混沌Chen系统的自适应追踪控制.根据Chen系统的结构特点选取合适的反馈方式，设计单输入自适应控制器，使Chen系统自适应追踪参数未知的Rossler系统的某一变量，并由Lyapunov直接方法证明误差信号渐近稳定于零.数值仿真结果表明该控制方法可行，且可以实现未知参数的辨识.     

延迟-非线性反馈控制混沌

提出了基于稳定性准则的延迟非线性反馈控制混沌的方法，即SC延迟非线性反馈控制法. 通过对混沌系统的适当分离，得到一个特殊的非线性函数，并利用混沌输出信号与其延迟信号的非线性函数的差，构造了连续反馈输入干扰，以控制混沌轨到某一期望的不稳周期轨上. 该方法继承了延迟反馈控制方法的优点，实现了自-控制过程. 另外由于该方法基于线性系统的稳定性准则，保证了控制的有效性. 控制过程可随时开始，具有简便、灵活性. 给出耦合Duffing振子的例子，数值模拟结果显示了SC延迟反馈方法控制的有效性. 关键词： 稳定性准则 混沌控制 延迟反馈 干扰     

半周期延迟-非线性反馈控制混沌

提出了基于稳定性准则的半周期延迟-非线性反馈控制混沌的方法，即SC(stability criterion)半周期延迟非线性反馈控制法.通过对混沌系统的适当分离，得到一个特殊的非线性函数，并利用混沌输出信号与其半周期延迟信号的非线性函数之和，构造了连续反馈输入干扰.该方法继承了延迟反馈控制方法及稳定性准则控制方法的优点，实现了有效的自控制过程；并克服了延迟反馈方法的限制，能将嵌入混沌吸引子中的自对称直接不稳周期轨稳定.控制过程可随时开始，具有简便、灵活性.数值模拟结果显示了SC半周期延迟-非线性反馈方法控制的有效性. 关键词： 稳定性准则 混沌控制 半周期延迟 非线性反馈     

一类非线性相对转动系统的混沌运动及多时滞反馈控制

建立一类含非线性粘滑摩擦力的两质量非线性相对转动系统的动力学方程. 研究此非线性相对转动系统在外激励作用下的混沌运动及多时滞反馈控制. 当系统在外激励作用下处于混沌状态时, 考虑引入多时滞反馈对系统的混沌运动进行控制. 应用Melnikov理论给出系统在Smale意义下的混沌临界条件, 研究了多时滞反馈对系统运动及混沌临界值的影响规律. 并结合系统相图、Poincare截面图和功率谱分析多时滞反馈参数对系统混沌运动的控制作用. 关键词： 多时滞 相对转动 控制 数值仿真     

基于区间系统理论的分数阶混沌系统同步

通过设计一个非线性反馈控制器,实现了分数阶混沌系统的同步.与其他的分数阶混沌系统同步方法相比,提出的控制器设计方法保留了部分误差系统中的非线性项,而没有完全抵消同步误差系统的非线性项,有效改善了误差系统的控制性能.同时,应用区间分数阶线性时不变系统稳定性原理和线性矩阵不等式技术,得到了一个新的分数阶混沌系统同步的充分条件,进而获得的控制器保证了混沌系统同步.仿真结果验证了提出方法的有效性. 关键词： 区间分数阶时不变系统 分数阶混沌系统 混沌同步     

基于直接延迟反馈的混沌反控制

在混沌有益时，有目的地产生混沌已经成为混沌学研究的热点问题，本文提出直接延迟反馈实现混沌的反控制，在非混沌系统中产生了混沌.该方法与间接延迟反馈控制方法相比，控制更加简单，更易于实现.该方法与Pyragas提出的延迟反馈混沌控制方法的控制器结构相同，因此，这种直接延迟反馈控制方法可以在需要混沌时产生混沌，不需要混沌时控制混沌，实现混沌控制和反控制的统一，为设计者提供最大的灵活性.针对参数处于非混沌区的Chen系统和Lorenz系统的仿真结果表明了该混沌反控制方法的有效性. 关键词： 混沌 反控制 直接延迟反馈     

Synchronization of Modified Chua＇s Circuit with x｜x｜ Function

This paper considers the chaos synchronization of the modified Chua＇s circuit with x｜x｜ function. We firstly show that a couple of the modified Chua systems with different parameters and initial conditions can be synchronized using active control when the values of parameters both in drive system and response system are known aforehand.Furthermore, based on Lyapunov stability theory we propose an adaptive active control approach to make the states of two identical Chua systems with unknown constant parameters asymptotically synchronized. Moreover the designed controller is independent of those unknown parameters. Numerical simulations are given to validate the proposed synchronization approach.     

THE MEASURE OF CHAOTIC PARAMETER FOR ONE-DIMENSIONAL UNIMODAL MAPPING f(x)=1-a|x|Z

The asymptotic behavior of the accumulation point a_∞ for the one-dimensional unimodal mapping (x)=1-a|x|^Z is studied in the Limit Z→∞. We find that a_∞～2-lnZ/Z, as Z→∞. The measure of chaotic parameter for this mapping is also investigated. It decreases exponentially as the exponent z increases.     

Control of degenerate Hopf bifurcations in three-dimensional maps

A feedback control method is proposed to create a degenerate Hopf bifurcation in three-dimensional maps at a desired parameter point. The particularity of this bifurcation is that the system admits a stable fixed point inside a stable Hopf circle, between which an unstable Hopf circle resides. The interest of this solution structure is that the asymptotic behavior of the system can be switched between stationary and quasi-periodic motions by only tuning the initial state conditions. A set of critical and stability conditions for the degenerate Hopf bifurcation are discussed. The washout-filter-based controller with a polynomial control law is utilized. The control gains are derived from the theory of Chenciner's degenerate Hopf bifurcation with the aid of the center manifold reduction and the normal form evolution.     

Dynamic behavior of time-delayed acceleration feedback controller for active vibration control of flexible structures

This paper addresses the design problem of the controller with time-delayed acceleration feedback. On the basis of the reduction method and output state-derivative feedback, a time-delayed acceleration feedback controller is proposed. Stability boundaries of the closed-loop system are determined by using Hurwitz stability criteria. Due to the introduction of time delay into the controller with acceleration feedback, the proposed controller has the feature of not only changing the mass property but also altering the damping property of the controlled system in the sense of equivalent structural modification. With this feature, the closed-loop system has a greater logarithmic decrement than the uncontrolled one, and in turn, the control behavior can be improved. In this connection, the time delay in the acceleration feedback control is a positive factor when satisfying some given conditions and it could be actively utilized. On the ground of the analysis, the developed controller is implemented on a cantilever beam for different controller gain–delay combinations, and the control performance is evaluated with the comparison to that of pure acceleration feedback controller. Simulation and experimental results verify the ability of the controller to attenuate the vibration resulting from the dominant mode.     

Control of a rotating cantilever beam using a torque actuator and a distributed piezoelectric polymer actuator

A torque actuator and a distributed piezoelectric polymer (PVDF) actuator are utilized for control of a rotating cantilever flexible beam. The torque control contains proportional and derivative (PD) feedback for rigid motion control and a PVDF actuator control for vibration damping. Unlike previous approaches in the literature in which the angular velocity feedback was utilized, in this study we propose to use the linear velocity feedback (L-type) in our controller design for feasible implementation and avoiding modal truncation. The stability of the system with the L-type control has been analyzed, using the concept of a virtual joint model. The advantage of the proposed scheme lies in easy implementation, avoidance of modal truncation, efficient suppression of the dominant mode of vibration, and allowing high-speed motions. Numerical examples demonstrate the effectiveness of the proposed approach.     

Synchronization between two different chaotic systems with nonlinear feedback control

This paper presents chaos synchronization between two different chaotic systems by using a nonlinear controller, in which the nonlinear functions of the system are used as a nonlinear feedback term. The feedback controller is designed on the basis of stability theory, and the area of feedback gain is determined. The artificial simulation results show that this control method is commendably effective and feasible.     

Active vibroacoustic control with multiple local feedback loops

When multiple actuators and sensors are used to control the vibration of a panel, or its sound radiation, they are usually positioned so that they couple into specific modes and are all connected together with a centralized control system. This paper investigates the physical effects of having a regular array of actuator and sensor pairs that are connected only by local feedback loops. An array of 4 x 4 force actuators and velocity sensors is first simulated, for which such a decentralized controller can be shown to be unconditionally stable. Significant reductions in both the kinetic energy of the panel and in its radiated sound power can be obtained for an optimal value of feedback gain, although higher values of feedback gain can induce extra resonances in the system and degrade the performance. A more practical transducer pair, consisting of a piezoelectric actuator and velocity sensor, is also investigated and the simulations suggest that a decentralized controller with this arrangement is also stable over a wide range of feedback gains. The resulting reductions in kinetic energy and sound power are not as great as with the force actuators, due to the extra resonances being more prominent and at lower frequencies, but are still worthwhile. This suggests that an array of independent modular systems, each of which included an actuator, a sensor, and a local feedback control loop, could be a simple and robust method of controlling broadband sound transmission when integrated into a panel.     

Design of output feedback controller for a unified chaotic system

In this paper, the synchronization of a unified chaotic system is investigated by the use of output feedback controllers; a two-input single-output feedback controller and single-input single-output feedback controller are presented to synchronize the unified chaotic system when the states are not all measurable. Compared with the existing results, the controllers designed in this paper have some advantages such as small feedback gain, simple structure and less conservation. Finally, numerical simulations results are provided to demonstrate the validity and effectiveness of the proposed method.     

Design of output feedback controller for a unified chaotic system

In this paper, the synchronization of a unified chaotic system is investigated by the use of output feedback controllers; a two-input single-output feedback controller and single-input single-output feedback controller are presented to synchronize the unified chaotic system when the states are not all measurable. Compared with the existing results, the controllers designed in this paper have some advantages such as small feedback gain, simple structure and less conservation. Finally, numerical simulations results are provided to demonstrate the validity and effectiveness of the proposed method.     

Controlling chaotic robots with kinematical redundancy

Robots with kinematical redundancy under the pseudoinverse control exhibit undesirable chaotic joint motion, which leads to erratic behaviors. In this study, we used the delayed feedback method to control chaotic motions of a planar 3R rigid and a planar 3R flexible redundant robot under the pseudoinverse control when the end-effector traces a closed-path repeatedly in the work space. It was demonstrated that chaotic motions of robots with kinematical redundancy can be turned into regular motion when the delayed feedback method was applied with some appropriate parameters. This study provides a new insight helpful to solve the repeatability problem of redundant manipulators.