终端滑模约束的时滞系统模型预测控制

终端约束区域和终端代价项在模型预测控制中起着关键的作用,针对输入受限的时滞系统,提出了终端滑模约束的模型预测控制．将满足输入约束的滑模面作为终端约束区域,使得终端约束区域扩大,有效缩短预测时域,减少计算量,有利于在线应用．最后通过仿真验证了所提方法的有效性．     

Squaring the circle: An algorithm for generating polyhedral invariant sets from ellipsoidal ones

This paper presents a new (geometrical) approach to the computation of polyhedral (robustly) positively invariant (PI) sets for general (possibly discontinuous) nonlinear discrete-time systems possibly affected by disturbances. Given a β-contractive ellipsoidal set , the key idea is to construct a polyhedral set that lies between the ellipsoidal sets and . A proof that the resulting polyhedral set is contractive and thus, PI, is given, and a new algorithm is developed to construct the desired polyhedral set. The problem of computing polyhedral invariant sets is formulated as a number of quadratic programming (QP) problems. The number of QP problems is guaranteed to be finite and therefore, the algorithm has finite termination. An important application of the proposed algorithm is the computation of polyhedral terminal constraint sets for model predictive control based on quadratic costs.     

Hybrid Fuzzy Modelling for Model Predictive Control

Model predictive control (MPC) has become an important area of research and is also an approach that has been successfully used in many industrial applications. In order to implement a MPC algorithm, a model of the process we are dealing with is needed. Due to the complex hybrid and nonlinear nature of many industrial processes, obtaining a suitable model is often a difficult task. In this paper a hybrid fuzzy modelling approach with a compact formulation is introduced. The hybrid system hierarchy is explained and the Takagi–Sugeno fuzzy formulation for the hybrid fuzzy modelling purposes is presented. An efficient method for identifying the hybrid fuzzy model is also proposed. A MPC algorithm suitable for systems with discrete inputs is treated. The benefits of the MPC algorithm employing the hybrid fuzzy model are verified on a batch-reactor simulation example: a comparison between the proposed modern intelligent (fuzzy) approach and a classic (linear) approach was made. It was established that the MPC algorithm employing the proposed hybrid fuzzy model clearly outperforms the approach where a hybrid linear model is used, which justifies the usability of the hybrid fuzzy model. The hybrid fuzzy formulation introduces a powerful model that can faithfully represent hybrid and nonlinear dynamics of systems met in industrial practice, therefore, this approach demonstrates a significant advantage for MPC resulting in a better control performance.     

基于区间控制的约束预测控制及约束影响

在实际被控过程中往往存在着很多约束条件,这使得预测控制的在线优化问题表现为非线性,难以获得控制律的具体表达式,为约束预测控制的分析造成困难基于Newton控制框架,针对线性系统离散状态空间的动态模型,考虑具有输入、输出区间约束条件下,基于区间控制思想的预测控制律的解析表达式,分别得到无约束和有约束情况下状态反馈控制律的...     

Constrained stabilization of continuous-time linear systems

In this paper we consider the stabilization problem for linear continuous-time systems, under state and control constraints. We show that the largest domain of attraction to the origin can be arbitrarily closely approximated by a polyhedral domain of attraction associated to a certain (continuous) feedback stabilizing control and we show how to use existing numeric procedures for discrete-time systems to solve the continuous-time problem. We propose a new discontinuous stabilizing control law for scalar-input systems which has the advantage of being successfully applicable to systems with quantized control.     

Stabilization of max-plus-linear systems using model predictive control: The unconstrained case

Max-plus-linear (MPL) systems are a class of event-driven nonlinear dynamic systems that can be described by models that are “linear” in the max-plus algebra. In this paper we derive a solution to a finite-horizon model predictive control (MPC) problem for MPL systems where the cost is designed to provide a trade-off between minimizing the due date error and a just-in-time production. In general, MPC can deal with complex input and states constraints. However, in this paper we assume that these are not present and it is only required that the input should be a nondecreasing sequence, i.e. we consider the “unconstrained” case. Despite the fact that the controlled system is nonlinear, by employing recent results in max-plus theory we are able to provide sufficient conditions such that the MPC controller is determined analytically and moreover the stability in terms of Lyapunov and in terms of boundedness of the closed-loop system is guaranteed a priori.     

多变量有约束过程的协调预测控制策略

针对多变量约束过程，提出了基于关联分析的协调预测控制策略，从而对系统控制性能和操作变量理想工作区起到了很好的协调作用，减少了在线控制计算工作量。     

约束Hammerstein系统输出反馈非线性预测控制

针对具有状态、输入和中间变量约束的Hammerstein系统,采用两步法控制策略,给出一种新的可保证闭环系统指数稳定的输出反馈非线性模型预测控制算法.基于Hammerstein系统的特殊结构,结合状态观测器给出无约束线性环节的输出反馈最优控制律,通过滚动优化一有限时域的约束优化问题计算实际控制量.给出保证闭环系统指数稳定的充分条件.以工业双环管聚丙烯装置牌号切换控制为例进行仿真,仿真结果验证该算法的有效性和实用性.     

Characterisation Of Receding Horizon Control For Constrained Linear Systems

This paper characterises the geometric structure of receding horizon control (RHC) of linear, discrete‐time systems, subject to a quadratic performance index and linear constraints. The geometric insights so obtained are exploited to derive a closed‐form solution for the case where the total number of constraints is less than or equal to the number of degrees of freedom, represented by the number of control moves. The solution is shown to be a partition of the state space into regions for which an analytic expression is given for the corresponding control law. Both the regions and the control law are characterised in terms of the parameters of the open‐loop optimal control problem that underlies RHC and can be computed off line. The solution for the case where the total number of constraints is greater than the number of degrees of freedom is addressed via an algorithm that iteratively uses the off‐line solution and avoids on‐line optimisation.     

Simultaneous Constrained Model Predictive Control and Identification of DARX Processes

In this work, we formulate a new approach to simultaneous constrained model predictive control and identification (MPCI). The proposed approach relies on the development of a persistent excitation (PE) criterion for processes described by DARX models. That PE criterion is used as an additional constraint in the standard on-line optimization of MPC. The resulting on-line optimization problem of MPCI is handled by successively solving a series of semi-definite programming problems. Advantages of MPCI in comparison to other closed-loop identification methods are (a) Constraints on process inputs and outputs are handled explicitly, (b) Deterioration of output regulation is kept to a minimum, while closed-loop identification is performed. The applicability of the method is illustrated by a number of simulation studies. Theoretical and computational issues for further investigation are suggested.     

Model predictive control for perturbed max-plus-linear systems

Model predictive control (MPC) is a popular controller design technique in the process industry. Conventional MPC uses linear or nonlinear discrete-time models. Recently, we have extended MPC to a class of discrete event systems that can be described by a model that is “linear” in the (max,+) algebra. In our previous work, we have only considered MPC for the deterministic noise-free case without modeling errors. In this paper, we extend our previous results on MPC for max-plus-linear systems to cases with noise and/or modeling errors. We show that under quite general conditions the resulting optimization problems can be solved very efficiently.     

参数未知系统直接广义预测控制

传统的广义预测控制(GPC)算法需要在线递推求解Diophantine方程及矩阵求逆,因此计算量很大,不适合对实时性要求高的控制系统.文中对参数未知线性系统提出一种直接广义预测控制(DGPC)方法.该方法直接辨识广义预测控制器参数θu,即基于广义误差估计值对控制器参数和广义误差估计值中的未知向量θu进行自适应调整.理论证明了该方法可使广义误差收敛到原点的一个小邻域内.仿真结果验证了此方法的有效性.由于实时性提高,并且不需要被控对象模型,该方法更利于实际应用.     

离散不确定系统的鲁棒预测控制

对预测控制中模型不确定性的处理一直是预测控制算法亟待解决的问题.考虑一类包含模型不确定性的控制对象模型,提出一种极大极小预测控制器设计方法.在滚动优化的每一步,考虑了状态变量不完全可测的情况,引入动态输出反馈的思想得到一个最坏条件下的性能指标的最优解,以最坏条件下的性能指标为求解优化问题的上界,通过线性矩阵不等式的方法求解凸优化问题.并从理论上证明了所设计的鲁棒预测控制器对不确定模型是稳定的.通过仿真算例的分析,证明了极大极小鲁棒预测控制器设计的有效性.     

预测控制中的稳态优化策略

预测柠制算法为了在自由度不足时按优先级优先保证基本控制目标,在自由度多余时充分利用自由度提高效益,在算法中引了优化 控制的策略,本文首先介绍和分析了以前对预测控制的改进工作,最后给出了基于目标规划思想的优化策略。     

不确定系统的稳定广义预测控制

针对一类有界不确定线性离散被控对象,采用Min-Max优化方法,提出一种新的稳定广义预测控制(MMSGPC)算法.引入内模控制结构,将干扰和不确定性从被控对象中分离出来,并利用局部反环节对其进行补偿;采用Min-Max优化方法,将终端约束条件转化为有界不确定性最差情况时应的线性方程;通过引入矩阵的Moore-Penrose逆,得到了终端约束线性方程的通解,并结合性能指标函数求得了最优控制律.通过仿真实例验证了该方法的稳定效果.     

约束分段仿射系统的鲁棒最小时间控制

针对一类有界附加扰动的分段仿射系统,提出了一种离线低复杂性的鲁棒预测控制方法-鲁棒最小时间控制.首先计算系统的最大鲁棒正不变集和相关的局部稳定控制律,然后基于最大鲁棒正不变集通过多参数规划离线迭代计算系统的鲁棒一步集,得到的最小时间控制器覆盖最大鲁棒可稳定集.提出的鲁棒最小时间控制确保系统状态在最小时间内进入鲁棒正不变...     

汽温系统的一种稳定预测控制方法设计

预测控制的最主要特征是滚动优化,该文深入分析了预测控制原有的滚动优化策略,提出了一种简化的预测控制方案,给出了算法步骤,并基于李亚谱诺夫稳定性理论对简化的控制算法进行了稳定性分析与设计.通过仿真研究在对单变量系统进行控制效果分析的基础上将其应用于200MW机组带汽-汽换热器的多变量汽温系统,结果表明,该方法具有算法简单,运算量小,运算速度快,控制量变化柔和,鲁棒性好的特点,尤其适用于复杂系统的控制,具有良好的应用前景,是对预测控制算法简化的一种有益的尝试.     

Linear offset-free Model Predictive Control

This work addresses the problem of offset-free Model Predictive Control (MPC) when tracking an asymptotically constant reference. In the first part, compact and intuitive conditions for offset-free MPC control are introduced by using the arguments of the internal model principle. In the second part, we study the case where the number of measured variables is larger than the number of tracked variables. The plant model is augmented only by as many states as there are tracked variables, and an algorithm which guarantees offset-free tracking is presented. In the last part, offset-free tracking properties for special implementations of MPC schemes are briefly discussed.     

基于多神经元模型的非线性系统预测控制

利用单神经元来逼近非线性系统在平衡点邻域内的泰勒展开式的直至二次项,首次提出了一种用多个单神经元模型来拟合非线性系统的建模方法,引入多模型参考轨迹,得到一种新的多模型预测控制。仿真结果表明,基于二阶泰勒级数得到的多神经元模型的预测控制器的性能要优于采用泰勒级数一阶线性项得到的多模型预测控制器,但计算量并未显著增加。     

基于状态观测器的约束鲁棒模型预测控制

模型不确定情况下的鲁棒问题是模型预测控制的一个根本问题。本文采用线性矩阵不等式(LMI)，研究多模型不确定性描述情况下的鲁棒模型预测控制问题。在输入输出约束条件下，最小化最坏情况下的无穷时域目标函数，获得保证系统稳定的基于状态观测器的状态反馈增益并且给出观测器增益的设计方法。实例说明算法可行且保证闭环系统渐近稳定。