带有补偿器的高层建筑结构滑模控制

针对高层建筑结构无法进行全状态反馈控制的问题。本文应用了带有补偿器的滑模控制(SlidingModeControlwithCompensator ,即SMC&C)方法。该方法有以下优点 :一是可以方便地均衡控制力与控制效果 ,二是更易于设计有限状态反馈的控制律。为了得到更好的控制效果 ,设计控制律时 ,采用了指数趋近律方法。数值算例验证了本文方法的有效性。     

柔性梁受迫振动时滞变结构控制的试验研究

时滞反馈控制是一种利用时滞进行系统控制的策略,目前对该控制策略的研究多是在理论上进行探讨,少有试验研究报道. 以受简谐激励的柔性悬臂梁为对象,开展时滞反馈控制的试验研究,给出了一个多时滞控制律的设计方法. 首先给出悬臂梁系统含有时滞项的控制模态状态方程; 然后对方程进行离散化和一种特殊的状态变量增广,得到形式上不含有时滞项的标准差分方程; 最后使用离散变结构控制的方法设计控制律. 试验中采用压电片作为作动器和外界激励,应变片作为传感器,分别考虑单时滞和双时滞的情况,通过试验验证了时滞反馈控制的可行性和有效性.关键词:柔性悬臂梁;变结构控制;时滞;实验      

抑制线振动台扰动的鲁棒自适应重复控制

针对线振动台系统中存在的非线性动态摩擦力及周期性纹波推力扰动,为获得线振动台较高的跟踪精度及鲁棒性能,提出了鲁棒自适应重复控制方法.该方法的控制律包含参数自适应控制、等效PID控制、重复空制和滑模控制.滑模控制用来镇定不确定性系统和保证自适应重复学习过程收敛,参数自适应律用来估计未知模型参数并予以补偿,重复控制用来抑制周期性扰动,提高周期性位置信号的跟踪性能.Lyapunov理论证明该控制律保证了闭环系统渐近稳定性.通过对线振动台系统仿真研究表明该控制律的有效性.     

机械轴承控制系统中的摩擦补偿

摩擦是机械轴承控制系统中最主要的扰动因素,也是影响系统低速跟踪性能的最主要因素。针对系统中动态摩擦力矩的影响,为了进一步提高系统的位置跟踪性能,提出一种重复自适应控制方法。该方法的控制律包含一个参数自适应律、等效PD控制律和一个重复控制律,其中,参数自适应律用来估计未知模型参数并予以补偿,而插入的重复控制器用来提高系统运行曲线的跟踪性能。系统中摩擦模型采用摩擦参数非一致性变化的LuGre动态模型。Lyapunov方法证明该补偿方法保证了闭环系统全局稳定性和对期望位置信号的渐近跟踪。最后,通过对控制系统的仿真研究验证了所提出方法的有效性。     

带有末端集中质量的双连杆柔性机械臂主动控制

对带有末端集中质量的双连杆柔性机械臂的主动控制进行了研究,给出系统的动力学方程,采用非线性解耦反馈控制方法分别得出系统大范围运动方程和柔性臂的动力学方程,采用机械臂逆动力学方法和LQR方法分别设计大范围运动控制律和压电作动器控制律.仿真结果显示,本文控制方法能够有效地进行机械臂的轨迹跟踪,柔性臂的弹性振动可以得到有效抑制.     

欧拉动弯曲问题的混沌控制

用周期激振力法、参数共振微扰法和延时反馈控制方法对欧拉动弯曲问题的混沌行为进行了控制，通过计算受控系统的Ｌｙａｐｕｎｏｖ指数来确定控制参数，得到受控后系统的高周期、低周期和准周期等稳定周期振动结果，。     

带可控臂绳系卫星释放及姿态控制

考虑带可控机械臂绳系卫星的面内运动, 研究其释放阶段的子星位置和姿态控制问题. 系绳释放时, 通过调整机械臂转角实现子星姿态的无动量轮控制. 控制律设计分为两步: 首先, 基于非线性最优控制理论, 研究在状态和控制约束下的子星位置及其姿态控制, 通过二阶Legendre伪谱法求解开环最优控制律; 其次, 以开环解为参考, 基于轨迹跟踪思想设计反馈控制器, 其中反馈控制增益由开环最优控制算法及数值插值确定. 最后通过算例研究验证了该方法的有效性.      

时变切换时滞反馈镇定混沌系统不稳定周期轨线

为提高经典时滞反馈控制镇定不稳定周期轨线的效果, 扩大受控周期轨线的稳定区域, 本文基于时变切换策略对经典时滞反馈控制进行改进, 提出了时变切换时滞反馈控制. 时变切换时滞反馈控制的控制信号仅在特定的时段中存在, 而在其他时段上不存在控制信号, 这与经典时滞反馈控制中具有固定的控制信号是不同的. 通过实例分析, 研究了时变切换时滞反馈控制在镇定不稳定周期轨线中的具体性能. 以反馈增益系数为变量, 计算受控周期轨线的最大条件Lyapunov指数, 得到了受控周期轨线的稳定区域随切换频率变化的关系曲线. 结果表明, 随着切换频率增大, 受控周期轨线的稳定区域呈现非平滑地变化. 当选取恰当的切换频率时, 时变切换时滞反馈控制的稳定区域显著大于经典时滞反馈控制的稳定区域. 在混沌控制的工程实践中, 控制信号常常受到一定的限制. 要实现对目标周期轨线的稳定控制, 就需要受控周期轨线具有足够大的稳定区域. 因此, 与经典时滞反馈控制相比, 本文提出的时变切换时滞反馈控制具有更广泛的应用前景.      

含时滞的参数不确定主动悬架离散系统鲁棒控制

针对主动悬架存在传输时滞和参数不确定性的控制问题，设计了含时滞的参数不确定鲁棒控制器。首先，运用线性分式变换方法推导出含时滞的参数不确定主动悬架状态空间方程，采用零阶保持器取值处理和双线性变换，建立主动悬架离散控制系统模型。其次，以车身垂向加速度为车辆悬架系统的最优化输出目标，采用Lyapunov泛函方法，推导出系统渐进稳定的鲁棒控制器充分条件，得到满足最优H_∞性能指标约束的反馈控制律，再通过求解线性矩阵不等式获得控制器参数。最后，进行数值算例仿真，结果表明，相较于只考虑时滞的控制器，含时滞的参数不确定鲁棒控制器具有更好的控制效果和鲁棒性，且受采样周期与不确定参数的耦合影响较小。     

控制存在时滞的线性系统主动控制的滑移模态方法

本文研究控制存在时滞的线性系统的滑模控制方法。在控制时滞量为采样周期的整数倍和非整数倍的两种情况下，通过采用零阶保持器，将包含时滞的连续系统转化为形式上不包含时滞的标准离散线性系统，然后分别进行切换函数和控制律的设计。所得出的切换面和控制律表达式中，除了含有当前的状态反馈外，还包含有前若干步控制项的线形组合。最后对某三自由度结构模型进行仿真计算，验证了所给控制方法的有效性。     

Control of a Hyperchaotic Discrete System

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Controlling chaotic oscillations of visco-elastic plates by the linearization via output feedback

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单足机器人周期跳跃控制的虚拟约束方法

研究单足机器人周期跳跃控制问题.弹簧支撑倒立摆模型可以比较准确地描述动物的跳跃行为,但无控制的自然跳跃抗干扰能力较差,一般采用轨迹跟踪控制方法实现单足机器人周期跳跃.当系统存在比较大的误差时,传统的时间轨迹跟踪控制方法存在明显的不足.引入虚拟约束技术,采用基于空间路径跟踪的控制方法可以克服时间轨迹跟踪的不足.采用点足机器人模型,并通过控制腿伸缩的方式为系统提供动力,将跳跃过程分为地面摆动和腾空飞行两个阶段,并通过起飞和着陆两个事件完成两个阶段之间的转换,整个系统模型属于欠驱动非光滑动力学系统.根据简化的动力学方程获得系统的虚拟约束解析表达式,并采用部分反馈线性化方法结合PD控制设计系统的控制律.分析了系统的混合零动力学方程,并证明了闭环系统的临界稳定性.仿真结果表明,提出的控制方法可以实现单足机器人的周期跳跃控制,并且对外部干扰具有较强的鲁棒性.     

Chaos in a pendulum with feedback control

We study chaotic dynamics of a pendulum subjected to linear feedback control with periodic desired motions. The pendulum is assumed to be driven by a servo-motor with small inductance, so that the feedback control system reduces to a periodic perturbation of a planar Hamiltonian system. This Hamiltonian system can possess multiple saddle points with non-transverse homoclinic and/or heteroclinic orbits. Using Melnikov's method, we obtain criteria for the existence of chaos in the pendulum motion. The computation of the Melnikov functions is performed by a numerical method. Several numerical examples are given and the theoretical predictions are compared with numerical simulation results for the behavior of invariant manifolds.     

Robust tracking control method based on composite nonlinear feedback technique for linear systems with time-varying uncertain parameters and disturbances

In this paper, the composite nonlinear feedback control method is considered for robust tracking and model following of uncertain linear systems. The control law guarantees that the tracking error decreases asymptotically to zero in the presence of time varying uncertain parameters and disturbances. For performance improvement of the dynamical system, the proposed robust tracking controller consists of linear and nonlinear feedback parts without any switching element. The linear feedback law is designed to allow the closed loop system have a small damping ratio and a quick response while the nonlinear feedback law increases the damping ratio of the system as the system output approaches the output of the reference model. A new collection of different nonlinear functions used in the control law are offered to improve the reference tracking performance of the system. The proposed robust tracking controller improves the transient performance and steady state accuracy simultaneously. Finally, the simulations are provided to verify the theoretical results.     

Arbitrary amplitude periodic solutions for parametrically excited systems with time delay

Periodic solutions for parametrically excited system under state feedback control with a time delay are investigated. Using the asymptotic perturbation method, two slow-flow equations for the amplitude and phase of the parametric resonance response are derived. Their fixed points correspond to limit cycles (phase-locked periodic solutions) for the starting system. In the system without control, periodic solutions (if any) exist only for fixed values of amplitude and phase and depend on the system parameters and excitation amplitude. In many cases, the amplitudes of periodic solutions do not correspond to the technical requirements. On the contrary, it is demonstrated that, if the vibration control terms are added, stable periodic solutions with arbitrarily chosen amplitude and phase can be accomplished. Therefore, an effective vibration control is possible if appropriate time delay and feedback gains are chosen.     

Periodic solution of a turbidostat model with impulsive state feedback control

In this paper, a turbidostat model with impulsive state feedback control is considered. We obtain sufficient conditions of the global asymptotical stability of the system without impulsive state feedback control. We also obtain that the system with impulsive state feedback control may have order one periodic solution, and the sufficient condition for existence and stability of order one periodic solution is gotten as well. For some special cases, it is shown that in the system an order two periodic solution may exist. Our results show that the control measure is effective and reliable.     

Time delay Duffing’s systems: chaos and chatter control

The effect of a delay feedback control (DFC), realized by displacement in the Duffing oscillator, for parameters which generate strange chaotic Ueda attractor is investigated in this paper. First, the classical Duffing system without time delay is analysed to find stable and especially unstable periodic orbits which can be stabilized by means of displacement delay feedback. The periodic orbits are found with help of the continuation method using the AUTO97 software. Next, the DFC is introduced with a time delay and a feedback gain parameters. The proper time delay and feedback gain are found in order to destroy the chaotic attractor and to stabilize the periodic orbit. Finally, chatter generated by time delay component is suppressed with help of an external excitation.     

Stabilization of discrete-time chaotic systems via improved periodic delayed feedback control based on polynomial matrix right coprime factorization

Delayed feedback control, proposed by Pyragas,is one of useful control methods of stabilizing unstable periodic orbits of chaotic systems without their exact information. This paper discusses an improved periodic delayed feedback control for the stabilization of the discrete-time chaotic systems. A technique to solve the generalized Sylvester matrix equation, based on polynomial matrix right coprime factorization, is introduced in order to give an explicit solution to the periodic gains of the closed-loop system. Moreover, some examples are demonstrated to show the effectiveness of the proposed method.