基于观测器的连续搅拌反应釜命令滤波控制

针对连续搅拌反应釜系统在实际应用过程中存在的外部扰动和状态不可测问题,设计了一种基于观测器的模糊自适应命令滤波控制策略。首先,利用模糊逻辑系统去逼近系统中存在的非线性函数,同时设计模糊状态观测器对系统的状态变量实时估计;其次,将自适应反步控制方法与命令滤波技术相结合,通过设计非线性扰动观测器准确估计系统的外部扰动,并在反步法设计过程中进行扰动补偿,从而使控制器的设计过程更简单,同时解决了传统反步法导致的“计算爆炸”问题。通过Lyapunov稳定性理论证明了闭环系统的稳定性。MATLAB仿真结果表明,所设计控制方案具有稳态误差小、控制精度高、抗干扰能力强,可直接对系统状态变量进行观测的优点。     

连续搅拌反应釜的固定时间命令滤波跟踪控制

针对一类连续搅拌反应釜系统的跟踪控制问题,提出一种基于反步法和模糊逻辑系统的自适应固定时间命令滤波控制方法.利用命令滤波器引入误差补偿机制消除滤波误差的影响,并解决反步法虚拟控制信号重复求导的问题;采用模糊逻辑系统对系统中存在的非线性部分进行逼近;利用固定时间控制方法使系统跟踪误差更迅速收敛至较小邻域内,且收敛时间不依赖系统初始状态;通过Lyapunov定理证明连续搅拌反应釜系统的闭环稳定性;利用Matlab/Simulink仿真实验验证所提出控制方法的有效性.与现有控制方法相比,该控制方法具有控制器结构简单、收敛速度快、控制精度高、无超调等优点.     

柔性关节机械手有限时间命令滤波反步控制

针对不确定柔性关节机械手的跟踪控制问题,设计了一种自适应神经网络有限时间命令滤波反步控制器.该控制器在经典反步控制技术的基础上,采用有限时间命令滤波器克服了传统反步法在计算虚拟信号导数时存在的复杂计算问题,并进一步设计了误差补偿机制,有效地补偿了命令滤波器造成的滤波误差.利用神经网络对系统模型中的不确定动态进行逼近,最...     

四旋翼飞行器有限时间命令滤波反步控制北大核心CSCD

针对具有参数不确定性和外部干扰的四旋翼飞行器轨迹跟踪控制问题,提出了一种基于命令滤波的有限时间自适应控制策略。通过引入有限时间命令滤波器,实现了对虚拟控制信号导数的快速逼近,进而有效地避免了传统反步设计法中存在的维数爆炸问题。设计新的分数阶误差补偿机制,快速移除了滤波误差影响,进一步提高了系统的控制性能。利用有限时间稳定性理论,严格证明了闭环系统中所有信号在有限时间内有界,且位置及姿态跟踪误差在有限时间内收敛到原点附近的邻域内。最后,仿真比较算例验证了所提控制方案的有效性。     

腈纶聚合过程连续搅拌反应釜解耦控制

腈纶聚合过程属于多输入多输出(MIMO)非线性系统,聚合连续搅拌反应釜(CSTR)温度和聚合反应转化效率是腈纶聚合生产的重要工艺指标。腈纶聚合过程的非线性、强耦合,参数时变性,使得这两个指标不能同时兼顾。针对腈纶水相聚合过程,采用自适应模糊控制方法,设计了腈纶聚合连续搅拌反应釜转化率和温度的解耦控制器。首先利用反馈线性化方法对腈纶水相聚合模型进行处理,设计系统的等效控制。模糊系统可以较好地逼近非线性函数,等效控制器中的非线性和参数不确定性,可采用模糊系统进行逼近。模糊参数的求解在线实时进行,参数自适应律由Lyapunov综合法获得。针对模糊逼近误差,采用minmax鲁棒最优控制方法,抑制误差干扰项对系统的影响。系统仿真结果表明,解耦控制方法能够在保证聚合过程的转化效率的前提下,调节反应温度。该方法对于提高聚合产品的性能,对提高产品的差别化率具有重要意义。     

不确定机械臂系统的自适应命令滤波反步渐近跟踪控制

研究具有未知参数和外部干扰机械臂的自适应渐近跟踪控制问题,提出一种自适应命令滤波反步策略,利用命令滤波器避免传统反步中对虚拟控制函数的微分计算,并建立误差补偿机制补偿滤波误差.与现有的针对机械臂的命令滤波反步跟踪控制相比,跟踪误差可以渐近收敛到零,并且只需要设计一个自适应参数.最后,通过仿真验证该方案的有效性.     

状态约束自主水下机器人的自适应有限时间跟踪控制

针对状态约束情况下自主水下机器人(autonomous underwater vehicle, AUV)的跟踪控制问题,提出了一种自适应命令滤波有限时间控制方案。该控制方案在保证系统有限时间收敛的前提下,不仅使用命令滤波器规避了虚拟控制信号高阶导数的使用,解决了计算复杂性问题,而且构建了有限时间误差补偿信号来避免由于使用滤波器而产生的滤波误差对控制性能的影响,同时利用径向基函数神经网络逼近技术处理系统中的未知非线性动态。最后,证明了所提出的控制器可以保证位置跟踪误差在有限时间内收敛到期望邻域内,同时不超过预先定义的状态约束。通过仿真实验验证了所提控制方案的合理性与可行性。     

连续搅拌反应釜的自适应输出反馈控制及参数整定

针对一类连续搅拌反应釜(CSTR),提出了基于扩张状态观测器和反步法的自适应控制方法,并结合连续动作强化学习器(CARLA)进行控制器参数整定.将CSTR视为包含不确定函数的非严格反馈非线性系统,利用扩张状态观测器对系统中的状态变量实时估计,并对不确定函数在线逼近,将系统补偿为线性二阶积分串联系统,为其设计反步法控制器.通过李雅普诺夫稳定性定理对系统稳定性进行分析,证明了闭环系统中所有信号均有界.最后,针对大量控制器参数难以人工整定的问题,设计CARLA算法快速搜索控制器参数最优值,提升了控制品质.仿真实验进一步验证了该方法的有效性.     

基于命令滤波反步的AUV轨迹跟踪控制

针对具有未建模动态及未知扰动的自主水下机器人(AUV)轨迹跟踪问题,考虑执行器饱和状况,提出了一种新型的命令滤波反步控制策略。首先,利用命令滤波器处理系统未建模动态及未知扰动,并基于反步法设计系统虚拟控制律,有效降低了控制策略的复杂度;然后基于李雅普诺夫(Lyapunov)稳定性理论,证明了闭环控制系统的稳定性;最后,利用仿真验证了所提控制策略的跟踪性能。仿真结果表明本文所提控制策略在模型参数不确定性的情况下,仍能实现对目标轨迹的有效跟踪。     

ISS feedback control redesign for continuous stirred tank reactors

In this paper a new nonlinear feedback control law for continuous stirred tank reactors, obtained by exact Input/Output (I/O) linearization and Sontag's input‐to‐state stability feedback control redesign methods, is studied. By the new feedback control law, a significant attenuation of the disturbance effect is guaranteed, with evident improvement with respect to control laws obtained by the exact I/O linearization method. The performed simulations validate the theoretical results. Copyright © 2010 John Wiley & Sons, Ltd.     

Robust control of oscillations in isothermal continuous stirred tank aerosol reactors

A method for the design of a robust non-linear feedback controller is presented for control of oscillations in isothermal continuous stirred tank aerosol reactors (CSTAR). The manipulative variable is the seeding or destruction of particles and the controlled variable is the number moment. Simulation results show that the control system is robust to modelling errors and that the performance of the controlled system is very good.     

Lyapunov-based control of non isothermal continuous stirred tank reactors using irreversible thermodynamics

In this paper, the thermodynamic availability function is used as a Lyapunov function for the practical derivation of non linear control laws for the stabilization of a large class of CSTRs far from the equilibrium. The strict convexity of the availability function is guaranteed as long as one of the extensive variables is fixed. In this study, we consider liquid mixture with constant volume, the constraint on the volume being insured by perfect regulation of the outlet flow of the CSTR. Several control laws are then derived which insure global asymptotic stability, exponential stability or simple asymptotic stability. These control laws are discussed regarding the magnitude and the dynamic variations of the control variable. It is shown that the availability function can be split into two parts: one corresponds to the mixing term and depends on mole numbers only and the other depends on both temperature and mole numbers. The two parts are positive and the second one is chosen as a new Lyapunov function. The use of this new Lyapunov function insures smooth variations of the control variable. An exothermal, first order chemical reaction leading to multiple steady-state operating points of the CSTR illustrates the proposed theory.     

Immersion and invariance adaptive control of a class of continuous stirred tank reactors

An immersion and invariance(I&I) manifold based adaptive control algorithm is presented for a class of continuous stirred tank reactors(CSTR) to realize performance-oriented control in this paper. The nonlinear contraction method is combined into the control law design to render the closed-loop CSTR system globally asymptotically stable, firstly. Then, the I&I method is used to form the adaptation law such that the off-the-manifold coordinate(the parameter estimation error) converges to zero using P-monotone property enforced by selecting tuning function in manifold. As a result, the state of the closed-loop CSTR converges to its desired value asymptotically. The simulation is given to illustrate the effectiveness of the presented algorithm.     

Improved fractional augmented control strategies for continuously stirred tank reactors

Controlling concentration and temperature of continuously stirred tank reactor (CSTR) is an extremely challenging task in chemical process industries. This is because conventional unity feedback schemes do not guarantee stable operating conditions for the CSTR process. Therefore, fractional calculus is augmented with multi-loop control to achieve enhanced stability and closed-loop performance than unity feedback structure in this work. Accordingly, three different fractional-order-based novel multi-loop control structures are proposed based on time domain analysis. In two of the proposed strategies, fractional-order PID controller (FOPID) and internal model control (IMC)-based FOPID controller with fractional filter are used in the inner-loop. Moreover, fractional-order-based Lyapunov stability rule of model reference adaptive control (MRAC) is used in outer-loops for both of the above mentioned methods. Finally, an advanced multi-loop predictor with FOPD controller in the inner-loop and FOIMC controller in the outer-loop is also proposed. In this work, fractional-order, filter parameters, and FOPID settings are obtained by minimizing multi-objective functions using modified particle swarm optimization (PSO) algorithm. Closed-loop responses and control efforts of the proposed control strategies are compared with that of FO-Lyapunov-based MRAC scheme. Quantitative performance analysis is also carried out on all proposed methods based on error metrics and total variation of the control signal.     

Local observability and controllability of stirred tank reactors

This paper deals with the observability and controllability properties of the linearized tangent dynamic model of (bio)chemical processes in isothermal stirred tank reactors (STRs). It is shown that a necessary condition for the observability (controllability) of isothermal (bio)chemical processes is that the number of measured components (the number of control inputs) is larger than or equal to the number of process components minus the number of reactions involved in the process. This gives a simple test for detecting possible lack of observability and/or controllability of isothermal STRs.     

连续搅拌釜式反应器的自耦比例–积分–微分控制

针对一类参数不确定的连续搅拌釜式反应器,使用了一种与被控对象无关的自耦比例–积分–微分(autocoupling proportional-integral-differential, ACPID)控制方法.该方法将系统内部所有不确定因素及外部扰动定义为一个总扰动,建立了以总扰动为激励的受控误差系统,并根据ACPID镇定规则建立了连续搅拌釜式反应器(continuous stirred tank reactor, CSTR)的ACPID控制系统.理论分析了ACPID控制系统的鲁棒稳定性和抗扰动鲁棒性.仿真结果表明了ACPID控制系统的有效性,在CSTR稳态调节控制领域具有重要的应用价值.     

基于有限时间指令滤波的非线性系统固定时间预设性能控制

针对一类严格反馈非线性系统,提出一种基于有限时间指令滤波的自适应固定时间预设性能控制策略.首先,引用非线性映射技术及适当的误差变换,建立等效的误差模型;其次,综合利用反步法、固定时间控制和自适应控制等方法,设计一种基于有限时间指令滤波的预设性能跟踪控制器.该策略应用指令滤波器解决了反步法中对虚拟控制律反复求导问题,减轻了计算负担.此外,预设性能控制和固定时间控制保证了系统的跟踪误差能够在固定时间内收敛到预设性能函数限定的范围内,其收敛时间与系统初始条件无关,且确保系统中全部信号在有限时间均达到有界区域.理论分析与仿真验证均表明了所提出设计方法的有效性.