基于FX-LMS算法的微振动主动隔振控制系统开发

控制系统是基于压电智能结构的各类微振动主动隔振系统的核心部分,而控制性能好、运算快速、实现方便的控制算法则是控制系统开发的关键.基于FIR数字滤波器,并应用FX-LMS自适应算法,对基于压电智能结构的各类微振动主动隔振系统的控制算法进行推导,并对其实现过程进行分析,以便于控制系统开发.在此基础上,利用该FX-LMS算法开发了某一维微振动主动隔振平台的自动控制系统,用于对该算法的控制效果进行实验测试和验证.实验结果表明,所推导的FX-LMS算法具有良好的控制效果,应用领域广阔.     

混沌系统脉冲控制及其Matlab仿真

研究Lü混沌系统的脉冲鲁棒镇定问题,得到其脉冲鲁棒镇定的充分条件,给出相应的脉冲控制律.通过应用Matlab中Simulink工具箱对Lü混沌系统进行仿真分析,说明脉冲控制是有效的镇定受扰动混沌系统的方法.     

非线性隔振系统振动特性分析

在舰艇振动较大的部位加装隔振系统是提高其自身声隐身性能最有效、最常用的方法之一,而混沌隔振方法可以很好地提高舰船线谱的隔振能力.以双层隔振系统为对象,建立两自由度非线性隔振系统的动力学模型,研究系统振动传递率特性及刚度对隔振效果的影响,采用数值积分方法分析不同激励幅值f1下系统随频率ω变化的分岔规律及非线性动力学行为.结果表明,当f1=12.0时,双层混沌隔振系统在1.11~1.18倍频区域出现混沌运动,该特征可以有效地降低结构噪声中的线谱成分,其整体隔振性能良好,验证了基于混沌理论的线谱控制方法的有效性.     

基于Matlab的模糊PID控制器设计与仿真研究

简单介绍了常规PID控制的优缺点和模糊控制的基本原理,介绍了模糊PID控制的系统结构,同时利用MATLAB中的SIMULINK和FUZZY工具箱进行了仿真研究。仿真结果表明,模糊PID具有比常规PID更好的控制效果。     

非线性混沌系统预测模型与仿真研究

主要研究由非线性混沌时序所确定的动力系统的预测方法及其应用，通过改进的最优化方法来估计模型的参数，并在其相空间中对时序的未来值进行预测，实例仿真，发现选取最佳的模型阶数能增加预测的准确程度，且混沌时序不可能进行长期的预测。     

主动隔振控制系统的研究

本文阐述主动隔振技术的基本原理和控制方法；介绍主动控制系统的试验构成；给出试验系统的控制软件框图，并对试验结果进行了数值分析．     

造纸机模糊控制系统设计及Matlab仿真

纸张水分是纸张最重要的质量指标之一。如果水分过高,会导致水分不均匀,容易产生气泡和水斑;如果水分过低,会导致纸张变脆,强度减弱,甚至纸张破裂。同时,影响纸张水分的因素众多,整个过程为多变量过程,变量之间存在着相互耦合。采用解耦方法将多变量系统解耦为单变量系统,并采用模糊控制器控制纸张水分,并在Matlab中进行了仿真验证。     

轿车动力总成主动隔振最优控制研究

介绍压电作动器与被动悬置串联组成的轿车动力总成主动悬置系统,分析了隔振系统的数学模型,采用最优控制原理提出了实施方法。     

非线性混沌系统预测模型与仿真研究

主要研究由非性线混沌时序所确定的动力系统的预测方法及其应用,通过改进的最优化方法来估计模型的参数,并在其相空间中对时序的未来值进行预测,实例仿真,发现选取最佳的模型阶数能增加预测的准确程度,且混沌时序不可能进行长期的预测.     

Active multivariable vibration isolation for a helicopter

The compensation of vibrations generated by the rotor of a helicopter and transmitted to the cabin is of great importance for rotorcraft design. These vibrations occur at discrete, well known frequencies, the so-called rotor-blade harmonic frequencies. In this paper the application of active control technology is investigated for vibration compensation. The multivariable mode of the helicopter is first decoupled in three subsystems. Then, a compensator is developed, which isolates the cabin from the oscillating rotor/gear-box unit at the first harmonic frequency and at the same time fixes the cabin to the rotor/gear-box unit for ascend or descend maneuvers.     

Two-sensor control in active vibration isolation using hard mounts

To isolate precision machines from floor vibrations, active vibration isolators are often applied. In this paper, a two-sensor control strategy, based on acceleration feedback and force feedback, is proposed for an active vibration isolator using a single-axis active hard mount. The hard mount provides a stiff support while an active control system is used to get the desired isolation performance. In our previous work, we showed that a sensor fusion control strategy for active hard mounts can be used to realize three performance objectives simultaneously: providing isolation from floor vibrations, achieving a low sensitivity for direct disturbance forces, and adding damping to internal modes of the supported precision machine. In the present work, an enhanced control strategy is presented, referred to as two-sensor control. We will show that two-sensor control outperforms sensor fusion, because it has more possibilities for loop-shaping and has better stability properties. The two-sensor control strategy is successfully validated on an experimental setup.     

Supervisory fault tolerant control for a class of uncertain nonlinear systems

This paper focuses on the design of a unique scheme that simultaneously performs fault isolation and fault tolerant control for a class of uncertain nonlinear systems with faults ranging over a finite cover. The proposed framework relies on a supervisory switching among a family of pre-computed candidate controllers without any additional model or filter. The states are ensured to be bounded during the switching delay, which ends when the correct stabilizing controller has been selected. Simulation results about a flexible joint robotic example illustrate the efficiency of the proposed method.     

Active vibration isolation based on model reference adaptive control

High-performance instruments are very sensitive to vibrations and jitters. In this article, a new approach towards multi-degree-of-freedom (DOF) active vibration isolation and its application in spacecraft jitter suppression are presented. Model reference adaptive control (MRAC) with acceleration feedback is used to isolate random disturbances. However, a side effect of this algorithm is that displacements at low frequencies are amplified. Thus, the MRAC is augmented with proportional–integral–differential (PID) displacement feedback to suppress vibration displacements. The MRAC-PID composite control is applied to a 4-leg platform to isolate vibrations and suppress tip/tilt jitters. The scheme is also used to isolate 6-DOF vibrations and steer the payload of a flexible spacecraft. Satisfactory performance of vibration isolation and jitter attenuation has been observed.     

Ｓｔｅｗａｒｔ主动隔振平台的神经网络自适应控制

针对Stewart主动隔振平台,提出一种基于径向基函数(RBF)神经网络的多输入多输出自适应隔振控制方法.考虑外界振动对Stewart主动隔振平台动态特性的影响,建立了隔振平台在工作空间中的动力学模型.推导出RBF神经网络的权值矩阵、高斯基函数中心和宽度的在线自适应调节律,以使神经网络快速逼近系统的非线性动态函数.应用Lyapunov稳定性理论,证明了在扰动力和神经网络逼近误差有界的条件下,闭环控制系统滤波误差和RBF神经网络各调节参数估计误差的一致最终有界.仿真结果表明,该控制方法能有效地抑制不同方向的低频有界振动.     

一类非线性系统的次优控制研究

考虑一类关系度不确定且零动态稳定的非线性系统的控制器设计问题．利用预测控制概念,通过选用较为全面的二次型性能指标,对输出进行高阶泰勒级数展开,推导出一种非切换的解析次优控制律,进而得出了在该控制律下闭环系统局部稳定的充分条件．仿真例子验证了该控制算法具有较好的动态性能,与已有的近似线性化方法相比,显示了该控制策略的优越性．     

一种新型浮筏的模糊减振控制

本文针对带有电流变液智能阻尼器的新型浮筏装置提出了前馈和反馈两种模糊控制策略并进行了实验研究.前馈模糊控制策略根据浮筏所受到的振动激励信号的主频特性来确定模糊控制器的控制规则,反馈模糊控制策略则是根据簧载质量的位移响应来制定控制规则,二者的最终目的都是通过模糊控制算法来得到最优的电流变液阻尼器控制电压,达到期望的隔振效果.实验结果证明,两种模糊控制策略控制下的浮筏隔振系统的隔振性能都要远远好于传统的最优被动浮筏隔振系统.     

Adaptive output control of a class of uncertain chaotic systems

In this paper, a new observer-based backstepping output control scheme is proposed for stabilizing and controlling a class of uncertain chaotic systems. The controller is designed through the use of a robust observer and backstepping technique. We firstly show that many chaotic systems as paradigms in the research of chaos can be transformed into a class of nonlinear systems in the feedback form. Secondly, the synchronization problem is converted to the tracking problem from control theory, thereby leading to the use of state observer design techniques. A new observer is utilized to estimate the unmeasured states. Unlike some existing methods for chaos control, no priori knowledge on the system parameters is required and only the output signal is available for control purpose. The Lyapunov functions are quadratic in the state estimates, the observer errors and the parameter estimation error based on the backstepping technique. It is shown that not only global stability is guaranteed by the proposed controller, but also both transient and asymptotic tracking performances are quantified as explicit functions of the design parameters so that designers can tune the design parameters in an explicit way to obtain the desired closed-loop behavior.     

Affine and predictive control policies for a class of nonlinear systems

The input-state linear horizon (ISLH) for a nonlinear discrete-time system is defined as the smallest number of time steps it takes the system input to appear nonlinearly in the state variable. In this paper, we employ the latter concept and show that the class of constraint admissible N-step affine state-feedback policies is equivalent to the associated class of constraint admissible disturbance-feedback policies, provided that N is less than the system’s ISLH. The result generalizes a recent result in [Goulart, P. J., Kerrigan, E. C., Maciejowski, J. M. (2006). Optimization over state feedback policies for robust control with constraints. Automatica, 42(4), 523-533] and is significant because it enables one: (i) to determine a constraint admissible state-feedback policy by employing well-known convex optimization techniques; and (ii) to guarantee robust recursive feasibility of a class of model predictive control (MPC) policies by imposing a suitable terminal constraint. In particular, we propose an input-to-state stabilizing MPC policy for a class of nonlinear systems with bounded disturbance inputs and mixed polytopic constraints on the state and the control input. At each time step, the proposed MPC policy requires the solution of a single convex quadratic programme parameterized by the current system state.     

Event-triggered sliding mode control for a class of nonlinear systems

ABSTRACT

Event-triggering strategy is one of the real-time control implementation techniques which aims at achieving minimum resource utilisation while ensuring the satisfactory performance of the closed-loop system. In this paper, we address the problem of robust stabilisation for a class of nonlinear systems subject to external disturbances using sliding mode control (SMC) by event-triggering scheme. An event-triggering scheme is developed for SMC to ensure the sliding trajectory remains confined in the vicinity of sliding manifold. The event-triggered SMC brings the sliding mode in the system and thus the steady-state trajectories of the system also remain bounded within a predesigned region in the presence of disturbances. The design of event parameters is also given considering the practical constraints on control execution. We show that the next triggering instant is larger than its immediate past triggering instant by a given positive constant. The analysis is also presented with taking delay into account in the control updates. An upper bound for delay is calculated to ensure stability of the system. It is shown that with delay steady-state bound of the system is increased than that of the case without delay. However, the system trajectories remain bounded in the case of delay, so stability is ensured. The performance of this event-triggered SMC is demonstrated through a numerical simulation.