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聚酯生产过程质量指标软测量和优化控制系统 总被引:2,自引:0,他引:2
以大型聚酯工业生产过程为对象,总结了指标的软测量和优化控制系统软件的总体结构。该软件由以模型为基础的关键质量指标的软测量与可在DCS系统上,及计算机控制语言(MATLAB)平台上,在线实时运行的PET优化控制软件系统两部分组成。控制软件包括质量指标在线检测系统、酯化率在线开环优化操作指导、酯化率预测控制系统、终缩聚粘度神经元网络自适应控制系统和反应釜位故障诊断系统。该软件已应用于指导和控制实际生产过程。 相似文献
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The problem considered in this paper deals with the control of linear discrete-time stochastic systems with unknown (possibly time-varying and random) gain parameters. The philosophy of control is based on the use of an open-loop feedback optimal (OLFO) control using a quadratic index of performance. It is shown that the OLFO system consists of 1) an identifier that estimates the system state variables and gain parameters and 2) a controller described by an "adaptive" gain and correction term. Several qualitative properties and asymptotic properties of the OLFO adaptive system are discussed. Simulation results dealing with the control of stable and unstable third-order plants are presented. The key quantitative result is the precise variation of the control system adaptive gains as a function of the future expected uncertainty of the parameters; thus, in this problem the ordinary "separation theorem" does not hold. 相似文献
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Yulong Tuo Yuanhui Wang Simon X. Yang Mohammad Biglarbegian Mingyu Fu 《International Journal of Control, Automation and Systems》2018,16(4):1648-1659
For floating production storage and offloading (FPSO) vessels, a dynamic positioning controller is necessary because using only a mooring system is not possible to keep the ship within a predefined region. Position control of the FPSO vessel is extremely challenging due to model uncertainties and unknown control coefficients. This paper develops a new robust adaptive positioning controller consisting of several components: adaptive law, dynamic surface control (DSC) technology, sigmoid tracking differentiator (STD), Nussbaum gain function, and structural reliability index. Model uncertainties can be estimated by the adaptive law derived from the Lyapunov theory. The DSC technology is used to eliminate repeated differentiation by introducing first-order filtering of the virtual control. The chattering-free STD with the characteristics of global fast convergence can estimate the derivatives of model uncertainties that are difficult to calculate directly. Therefore, the DSC and STD techniques make the proposed controller simpler to compute and easier to implement in engineering practice. Most of the traditional controllers require the information about the control coefficients to guarantee the stability of the closed-loop system while the Nussbaum gain function can remove the requirement for a priori knowledge of the sign of control coefficients. The capacity of the mooring system can be fully utilized to position the FPSO vessel by adjusting the structural reliability index on the premise of ensuring the safety of mooring lines, and hence less control effort is needed for the positioning controller. Simulations using two sets of system parameters demonstrate the proposed controller’s effectiveness. In addition, a qualitative comparison with the adaptive backstepping controller shows that our proposed controller is computationally more efficient and does not require a priori knowledge of the sign of control coefficients. A quantitative comparison with robust adaptive controller without the structural reliability shows that less control effort is needed using our proposed controller. 相似文献
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基于工控组态软件的模型参考自适应液位控制系统的设计 总被引:1,自引:0,他引:1
针对FESTO过程控制系统液位站中的液位控制问题,提出了一种利用工控组态软件和ActiveX特性扩充组态软件控制功能实现模型参考自适应控制的新方法;重点描述了控制策略、现场信号和组态软件之间的有机结合,为在工业控制领域中使用组态软件来完成复杂的控制算法开辟了新的途径;从实验结果的两组响应曲线可以看出,采用自适应控制时系统的性能指标要优于常规PID控制;因此,可以证明文中设计的自适应控制系统可以实现对液位的稳定控制;系统具有形象直观、实时性好、编程简单等特点,满足了工业控制的要求。 相似文献
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含有界扰动系统的多模型自适应控制 总被引:8,自引:1,他引:7
对含有有界扰动和参数不确定性的离散时间被控对象建立多个辨识模型, 覆盖被控对象的参数不确定性. 给定指标切换函数, 构成多模型自适应控制器. 引入“局部化”技术, 在保持计算精度的同时, 提高了计算速度. 同时证明, 多模型自适应控制可以保证闭环系统输入输出稳定, 且保证对给定有界参考输入、被控对象输出可在一给定界范围内跟踪参考输入. 相似文献
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This article proposes a new technique for the tuning of a discrete adaptive controller that is designed based on Lyapunov stability concepts. The tuning is based on the minimisation of a performance index that can be calculated from a generalised eigenvalue problem (GEVP) using LMI's (Linear Matrix Inequalities). The proposed technique results in an adaptive controller with time-varying tuning gains. The solution is based on an approximation of the optimal dual adaptive control problem. The tuning technique was used to perform on-line control of a first-order system and an isothermal and a non-isothermal CSTR. The results show that the proposed approach provides better performance than an adaptive algorithm with the same structure, but with constant adaptation gains. Also, the proposed algorithm is shown to be superior to an adaptive controller based on a Recursive Least Squares (RLS) estimator during sudden changes in model parameters. 相似文献
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针对云平台风险访问控制模型中风险评估指标权重主观设定且固定的问题,提出自适应风险评估指标权重分配方法。首先,通过带约束的多元线性回归设计自适应风险评估指标权重分配模型;然后,提出并优化配方回归算法求解相应权重;最后,构建带有自适应权重分配的风险值量化公式,动态计算访问请求的风险值。实验结果表明,该方法与动态风险访问控制(DRAC)模型、基于系统安全风险的访问控制模型相比,在训练集数量级相同的条件下,其风险值的准确率和灵敏度平均提升了2.8%和18.5%、1.7%和18.7%。该方法与DRAC模型、基于动态属性的风险感知访问控制(DA-RAAC)模型以及基于系统安全风险的访问控制模型相比,在访问请求数量相同的条件下,响应时间平均缩短了9.2%、34.6%和96.6%。所提方法在大并发用户数情况下所得风险值有较高的准确率和灵敏度,且响应时间更短,更适用于云环境。 相似文献
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时滞扩散性复杂网络同步保性能控制 总被引:6,自引:4,他引:2
针对节点扩张的时滞复杂网络系统, 在节点扩张的条件下, 讨论此类系统的同步保性能控制问题. 首先采用自适应控制方法, 利用Lyapunov-Krasovskii稳定性理论,结合矩阵不等式的凸优化问题处理方法, 得出了时 滞复杂网络系统保性能控制器存在的充分条件; 当系统节点的扩张后, 在原有自适应控制器不能使系统同步稳定的条件下, 设计脉冲控制器, 利用牵制控制原理使系统达到稳定同步. 所设计的自适应动态反馈控制器在保证系统的渐近稳定条件下使系 统性能指标满足一定的要求. 最后给出一个数值仿真说明其有效性. 相似文献
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基于自适应动态规划的一类带有时滞的离散时间非线性系统的最优控制策略 总被引:4,自引:3,他引:1
针对一类状态和控制变量均带有时滞的非线性系统的带有二次性能指标函数最优控制问题, 本文提出了一种基于新的迭代自适应动态规划算法的最优控制方案. 通过引进时滞矩阵函数, 应用动态规划理论, 本文获得了最优控制的显式表达式, 然后通过自适应评判技术获得最优控制量. 本文给出了收敛性证明以保证性能指标函数收敛到最优. 为了实现所提出的算法, 本文采用神经网络近似性能指标函数、计算最优控制策略、求解时滞矩阵函数、以及给非线性系统建模. 最后本文给出了两个仿真例子说明所提出的最优策略的有效性. 相似文献
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An adaptive servo control law with input constraints is derived for application to linear time-invariant systems with unknown parameters and two sampling rates: a slower one for the output, and a faster one for the input. The error between the actual and a reference performance index is shown to be bounded by the product of a finite gain and the parameter estimation error in the limit sense. Sufficient conditions for parameter convergence are proven under which the performance of the multirate, adaptive constrained control system asymptotically approaches that of the analogous single (fast) rate, constrained control system with known, constant parameters. The advantages of the multirate, adaptive constrained control algorithm are demonstrated by numerical simulations. 相似文献
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In this article, a robust adaptive control scheme for robotic manipulators is designed based on the concept of performance index and Lyapunov's second method. Compensators are selected for a given feedback system by using a quadratic performance index. Then the stability of the system is proven based on Lyapunov's method, where a Lyapunov function and its time-derivative are derived from the selected compensators. In the process of stabilization, stability bounds are obtained for disturbances, control gains, adaptation gains, and desired trajectories, in the presence of feedback delay due to digital computation and first-order hold in the control loop. © 1994 John Wiley & Sons, Inc. 相似文献
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Nikolaos A. Sofianos 《International journal of systems science》2013,44(8):1546-1565
A new indirect adaptive switching fuzzy control method for fuzzy dynamical systems, based on Takagi–Sugeno (T–S) multiple models is proposed in this article. Motivated by the fact that indirect adaptive control techniques suffer from poor transient response, especially when the initialisation of the estimation model is highly inaccurate and the region of uncertainty for the plant parameters is very large, we present a fuzzy control method that utilises the advantages of multiple models strategy. The dynamical system is expressed using the T–S method in order to cope with the nonlinearities. T–S adaptive multiple models of the system to be controlled are constructed using different initial estimations for the parameters while one feedback linearisation controller corresponds to each model according to a specified reference model. The controller to be applied is determined at every time instant by the model which best approximates the plant using a switching rule with a suitable performance index. Lyapunov stability theory is used in order to obtain the adaptive law for the multiple models parameters, ensuring the asymptotic stability of the system while a modification in this law keeps the control input away from singularities. Also, by introducing the next best controller logic, we avoid possible infeasibilities in the control signal. Simulation results are presented, indicating the effectiveness and the advantages of the proposed method. 相似文献