基于改进VRFT算法的PID控制器参数整定

分析虚拟参考反馈参数整定（VRFT）设计方法和内模控制（IMC）方法的内在关系,提出一种改进的VRFT—PID参数整定方法。该方法的基本思想是将运行一段时间的过程输入输出数据添加到原始数据序列中,用来更新传统VRFT设计方法中的离线数据。然后利用VRFT使性能指标最小时的参数即为控制器参数的设计思想来整定PID控制器。仿真结果表明,改进的VRFT-PID整定方法优于传统的VRFT-PID方法。     

ADAPTIVE ACTUAL PID CONTROL WITH AN ADJUSTABLE IDENTIFICATION INTERVAL

A method of design for an adaptive PID controller in an “actual” form is developed. The controller is expressed as an ideal PID controller with a low-pass filter. The parameters of the controller are determined by using the ITAE criterion based on a first-order plus dead time model which is directly obtained from an identified second-order model. In comparison with the ideal PID controller, the actual one gives better results especially for systems with noises.     

基于VRFT的IMC-PID方法及其在水厂浊度控制中的仿真研究

针对城市供水出水浊度过程的大惯性、大时滞、非线性以及时变等特点,将虚拟参考反馈整定数据驱动方法引入到IMC-PID控制器的整定中来,提出了一种不基于模型参数的VRFT-IMC参数整定方法.该方法集合了内模控制鲁棒性强和数据驱动控制的自适应性两方面的优点,仿真表明其控制性能优于普通IMC-PID控制器,可望用于出水浊度等...     

基于神经网络和多模型的非线性自适应PID控制及应用

针对一类未知的单输入单输出离散非线性系统,提出了基于神经网络和多模型的非线性自适应PID控制方法。该方法由线性自适应PID控制器、神经网络非线性自适应PID控制器以及切换机构组成。采用线性自适应PID控制器可保证闭环系统所有信号有界;采用神经网络非线性自适应PID控制器可改善系统性能;通过引入合理的切换机制,能够在保证闭环系统稳定的同时,提高系统性能。理论分析表明,该方法能够保证闭环系统所有信号有界,如果适当地选择神经网络的结构和参数,系统的跟踪误差将收敛于任意给定的紧集。将所提出的方法应用于连续搅拌反应釜,仿真结果验证了所提出方法的有效性。由于该方法基于增量式数字PID控制器,在工业过程中有着广阔的应用前景。     

Low-gain internal model control PID controller design based on second-order filter

A design method is proposed for low-gain internal model control (IMC) proportional-integral-derivative (PID) controllers based on the second-order filter. The PID parameters are obtained by approximating the feedback form of the IMC controller with a Maclaurin series, in which the second-order filter is applied using the IMC approach to achieve a low-gain PID controller that is suitable for model mismatch problems. Analytical PID tuning rules based on the second-order filter are derived for several common-use process models. The second-order filter is designed from the desired time domain performances of maximum overshoot and settling time. Furthermore, the robustness of the IMC PID controller based on the second-order filter is analyzed, and results show that its robustness performance is better than the first-order filter under certain conditions. Finally, three categories of models divided by the ration of time constant and time delay are presented in the comparative numerical simulations to validate the effectiveness and generality of the proposed PID controller design method.     

不稳定时滞过程PID控制器时域直接设计法

直接在时域上设计不稳定时滞过程比例积分微分(PID)控制器.采取双回路三环节的控制结构,满足时域指标-阻尼系数的要求,并对积分增益进行优化.首先设计出满足时城指标要求的理想PID控制器,然后将微分运算等效移动到内部反馈支路,最后合并3个环节得到设定值加权PID控制嚣.仿真表明该方法是有效的,所整定的控制系统具有好的鲁棒...     

微结构注塑机注射速度控制及仿真研究

为了对注射速度进行精密控制,建立起一个液压控制系统,对该系统中影响注射速度的相关器件进行结构分析并且建立数学模型,针对注射速度非线性以及时变等特性,设计一种自适应模糊PID控制器,利用MATLAB软件建立仿真模型,对两种控制器下的注射速度曲线进行对比分析。结果表明,与传统PID控制器相比,自适应模糊PID控制器具有注射速度响应更迅速,稳态无误差和鲁棒性能好等优势。     

模糊自适应PID在陶瓷高温电加热炉中的实现

针对陶瓷高温电加热炉温控制系统的特点,设计了基于STC89C52单片机的温度控制系统的硬件,利用Keil C51软件开发系统编制了相应的程序,模糊自适应PID控制器在单片机系统中得到了实现.将该控制方案应用在陶瓷高温电加热炉控制系统中,具有调节时间短、超调量小的优良特性.     

Approximate Pole Placement with Dominance for Continuous Delay Systems by PID Controllers

It is well known that a continuous‐time feedback system with time delay has infinite spectrum and it is not possible to assign such infinite spectrum with a finite‐dimensional controller. In such a case, only the partial pole placement may be feasible and hopefully some of the assigned poles are dominant. But there is no easy way to guarantee dominance of the desired poles. In this paper, an analytical PID design method is proposed for continuous‐time delay systems to achieve approximate pole placement with dominance. Its idea is to bypass continuous infinite spectrum problem by converting a delay process to a rational discrete model and getting back continuous PID controller from its discrete form designed for the model with pole placement. Simulation results are included to illustrate the effectiveness of this method.     

TUNING PID CONTROLLER FOR OPEN-LOOP UNSTABLE PROCESSES WITH TIME DELAY

A calculation method of PID controller tuning for the first- and the second-order open-loop unstable process models with time delay is presented in this study. Optimum PID controller tuning data based on the models and minimum IAE criterion were obtained via Powell searching technique, and these data were then empirically correlated into several multiple-regression equations by a least-squares method. Thus PID controller tuning based on the models can easily be obtained by the calculation of these correlated equations. Simulation with a reset-feedback PID control algorithm has demonstrated that the proposed tuning method based on the first-order model can provide better results than the latest studies. In addition, simulation has also unveiled that tuning results based on the second-order models are superior to the first-order model for a higher-order process.     

Analytical design of PID controller cascaded with a lead-lag filter for time-delay processes

An analytical method for the design of a proportional-integral-derivative (PID) controller cascaded with a second-order lead-lag filter is proposed for various types of time-delay process. The proposed design method is based on the IMC-PID method to obtain a desired, closed-loop response. The process dead time is approximated by using the appropriate Pade expansion to convert the ideal feedback controller to the proposed PID·filter structure with little loss of accuracy. The resulting PID·filter controller efficiently compensates for the dominant process poles and zeros and significantly improves the closed-loop performance. The simulation results demonstrate the superior performance of the proposed PID·filter controller over the conventional PID controllers. A guideline for the closed-loop time constant, λ, is also suggested for the FOPDT and SOPDT models.     

基于在线子空间辨识的自适应预测控制

针对实际工业工程中存在非线性、时变的特点,提出一种基于子空间辨识的自适应预测控制方法。利用滚动窗口在线更新R阵,得到新的预测模型参数矩阵,通过比较更新前和更新后的预测误差来决定是否更新预测模型。将此控制方法应用于2-CSTR过程控制的仿真试验,通过与自适应模糊控制、PID控制器的比较,说明了该方法的优越性。     

An energy effective PID tuning method for the control of polybutadiene latex reactor based on closed-loop identification

The PBL (Polybutadiene Latex) production process is a typical batch process. Changes of the reactor characteristics due to the accumulated scaling with the increase of batch cycles require adaptive tuning of the PID controller being used. In this work we propose a tuning method for PID controllers based on the closed-loop identification and the genetic algorithm (GA) and apply it to control the PBL process. An approximated process transfer function for the PBL reactor is obtained from the closed-loop data by using a suitable closed-loop identification method. Tuning is performed by GA optimization in which the objective function is given by ITAE for the setpoint change. The proposed tuning method showed good control performance in actual operations.     

ADAPTIVE FUZZY MODEL BASED PREDICTIVE CONTROL OF AN EXOTHERMIC BATCH CHEMICAL REACTOR*

An adaptive fuzzy model based predictive control (AFMBPC) approach is presented to track the desired temperature trajectories in an exothermic batch chemical reactor. The AFMBPC incorporates an adaptive fuzzy modeling framework into a model based predictive control scheme to derive analytical controller output. This approach has the flexibility to cope with different fuzzy model structures whose choice also lead to improve the controller performance. In this approach, adaptation of fuzzy models using dynamic process information is carried out to build a predictive controller, thus eliminating the determination of a predefined fixed fuzzy model based on various sets of known input-output relations. The performance of the AFMBPC is evaluated by comparing to a fixed fuzzy model based predictive controller (FFMBPC) and a conventional PID controller. The results show the better suitability of AFMBPC for the control of highly nonlinear and time varying batch chemical reactors.     

典型大时变时滞系统神经网络模糊PID控制及应用

针对典型大时变时滞系统,设计了一种基于神经网络的模糊PID控制器.该控制器综合模糊逻辑、神经网络与PID调节的各自优点,既具有模糊控制简单和有效的非线性控制作用,又具有神经网络的学习和适应能力,同时还具备PID控制的广泛适应性.该控制器能实现系统参数大范围失配情况下的闭环鲁棒稳定,并使闭环系统达到设定值无静差跟踪及满意的动态性能.     

基于粒子群优化算法的球磨机制粉系统PID-ANN解耦控制器

球团厂钢球磨煤制粉系统是多变量强耦合、时滞、非线性以及生产工况变化大的复杂对象,其自动控制问题一直是控制界关注的热点。基于粒子群算法具有对整个参数空间进行高效并行搜索的特点以及PID神经网络的自调节和自适应特性,设计了具有PID结构的多变量自适应神经网络控制器。PID神经网络解耦控制方法被用来消除回路之间的耦合,神经网络连接权值由粒子群算法进行学习优化。仿真研究表明所建模型和所提控制方法具有较好的控制品质、良好的自适应解耦能力和自学习功能。该控制策略可在大范围内克服系统的非线性和强耦合问题,具有很高的工程实用价值。     

DYNAMIC FUZZY ADAPTIVE CONTROLLER FOR pH

Control of pH processes is very difficult due to nonlinear dynamics, high sensitivity at the neutral point, and changes in the concentrations of known or unknown chemical species. In this study, a dynamic fuzzy adaptive controller (DFAC) with a new inference mechanism is proposed and applied for the control of pH processes. The DFAC consists of a low-level basic control phase with a minimum rule base and a high-level dynamic learining phase with an updating mechanism to interact and modify the control rule base. The DFAC can self-adjust its fuzzy control rules using information from the process during on-line control and create new fuzzy control rules or modify the present control rules using its learning capability from past control trends. The controller is evaluated by applying it to a weak acid-strong base pH process with input disturbances and to another pH process that involve that has changes in acidic/buffering streams. The results of the DFAC with the new inference mechanism are compared with the known inference mechanisms, the fuzzy controller, the conventional PI controller, and also with an adaptive PID controller. The proposed DFAC provides better performance for set point tracking of the pH and rejection of load disturbances and buffering affects.     

Identification and Control for Unstable Processes of Three Dynamic Types

This article classifies the process dynamics involving one or two unstable poles into three types, which are of paramount importance in controller design. Necessary and sufficient conditions are addressed for gain and relay stabilizability of such dynamics. Two nonlinear elements, one being a relay, are employed to excite rich input-output data for identification. A procedure is then developed to identify an unstable delayed model of appropriate order (second or third order), followed by the optimal PID controller design established based on the weighted ISE index. The resultant controller can cope with both load disturbances and set-point changes simultaneously and provide good robustness by satisfying the maximum gain margin criterion. The method is tested with good results on a nonlinear CSTR process.     

Identification and Control for Unstable Processes of Three Dynamic Types

This article classifies the process dynamics involving one or two unstable poles into three types, which are of paramount importance in controller design. Necessary and sufficient conditions are addressed for gain and relay stabilizability of such dynamics. Two nonlinear elements, one being a relay, are employed to excite rich input-output data for identification. A procedure is then developed to identify an unstable delayed model of appropriate order (second or third order), followed by the optimal PID controller design established based on the weighted ISE index. The resultant controller can cope with both load disturbances and set-point changes simultaneously and provide good robustness by satisfying the maximum gain margin criterion. The method is tested with good results on a nonlinear CSTR process.     

ADAPTIVE DOMINANT POLE DESIGN OF PID CONTROLLERS BASED ON A SINGLE CLOSED-LOOP TEST

A novel method, based on a single experimental test under proportional feedback, has been developed to tune PID controllers on-line. The tuning method involving an identification scheme and a dominant pole design technique is ideal for automatic tuning. It also provides an adaptive algorithm to adjust the controller settings to achieve the desirable control performance satisfying the prescribed decay ratio and stability margin. A simulation study demonstrates that the method is valid for processes with large dead-times as well as open-loop underdamped processes.