AUTOMATIC TUNING OF PID CONTROLLERS THROUGH RESPONSE OPTIMIZATION OVER A FINITE TIME HORIZON

The input-output functional relationship of a plant is identified and expressed in explicit form over a finite time horizon. Several schemes (orthogonal expansions, ARMA and MA models) are shown to result in a similar problem formulation. The identified model is operated on the fixed structure of a discrete time PID controller, and the parameters of the latter calculated as to minimize a performance index that penalizes both the quadratic departure of the error from the desired value and large variations in the error signal therefore avoiding abrupt controller actions

Results from simulation are given in terms of tuning the PID controller of a triple effect evaporator that simulates a. real equipment used at the industry to obtain juice concentrate.     

CLOSED-LOOP TUNING METHOD BASED ON DOMINANT POLE PLACEMENT

Algorithms are developed based on dominant pole placement to arrive at PID controller settings which yield desired decay ratio and nearly minimum IAE and ITAE. The process is fitted to first-order plus time-delay via a closed-loop process reaction curve. Tuning rules for load changes, setpoint changes, and simultaneous changes in setpoint and load are expressed in simple-to-use correlation form. The proposed closed-loop tuning method are demonstrated to be far superior to numerous available methods in view IAE, ITAE, decay ratio, overshoot, normalized prediction horizon, and maximum log modulus.     

OPTIMALITY CHARACTERISTICS OF PI/PID CONTROLLERS: A COMBINED MIN-MAX/ISE INTERPRETATION

This communication addresses the tuning of PI and PID controllers on the basis of the IMC approach. The tuning is based upon a first order plus time delay (FOPTD) model and aims to achieve a step response specification. Through analysis it has been found that by using the IMC approach we get a PI or a PID depending on the rational approximation used for the time delay term. This article raises the question that the use of a PID instead of a PI controller should be based on another reason more related to the control objectives rather than the use of a better approximation for the time delay. An alternative tuning is presented here, from within the IMC formulation, based on a min-max optimization. From the tuning rule provided by this approach the optimum settings from an integral squared error criterion point of view are derived. The optimal controller results in being a PI controller. From this optimal controller as the starting point, the introduction of the derivative action can be seen as a detuning procedure that can increase the robustness of the controller. This approach provides further insight into the tuning of PI and PID controllers giving the (alternative) parameters a precise engineering meaning.     

自适应PID控制的安全保护的几点考虑

本文就自适应ＰＩＤ控制在实际应用中所面临的安全性问题，提出了针对安全保护的几点考虑。     

基于PID模糊控制的陶瓷窑炉温度控制系统的设计

分析了应用于陶瓷窑炉的PID模糊控制技术的基本原理、设计方法以及控制程序的计算机实现方法等。这是一种能抗干扰，不依赖于对象模型的实用智能控制技术。     

基于启发式知识和自适用遗传算法的复合材料铺层优化设计

一般针对复合材料层合板铺层优化设计的研究多侧重于算法的研究,没有考虑到铺层知识对铺层的约束.本文建立了基于启发式知识和自适应遗传算法的复合材料层合板铺层优化模型,采用带置信度的IF-THEN模糊表达方式表达层合板铺层启发式知识,以蔡-希尔(Tsai-Hill)强度准则建立自适用遗传算法的适应度函数,在原有约束的基础上增加了铺层启发式知识约束.算例应用上述模型求解层合板的最佳铺层顺序,并将该结果和没有应用铺层知识约束的优化结果进行比较,证明了该模型的优越性和实用性.     

基于系统辨识的PID参数自整定算法在合成氨装置中的应用

从中石化湖北化肥分公司合成氨装置DCS系统中PID参数整定的实际出发,介绍了几种国内外PID参数自整定方法,分析它们的优缺点及存在的问题,提出一种新的基于系统辨识的PID参数自整定算法.论述基于VB的PID参数自整定软件开发,给出PID参数自整定程序设计界面.将这种PID自整定算法在中石化湖北化肥分公司DCS系统中进行应用实验,得出PID参数自整定前后PV趋势对比图,从而验证这种PID自整定算法的可行性.     

从系统工程视角试论基于基团贡献法的树脂基体的分子设计

从系统工程的观点,提出了基于基团贡献法的树脂基体的计算机辅助分子设计的框架轮廓,以图促进潜在地作为传统树脂基体研发方法的有效替代或者至少是有益的补充的树脂基体的计算机辅助分子设计方法的发展。