基于Smith预估器的模糊PID调车自动驾驶系统速度控制研究

针对铁路站场调车作业的复杂性,研发基于调车的自动驾驶系统可降低劳动强度并提高车站作业效率,而速度控制策略是系统的重点和难点。根据调车牵引控制系统和制动控制系统特性,建立传递函数模型,并对模型参数的不稳定因素进行分析;利用Smith预估方法处理时滞系统的优势,结合模糊PID算法,设计基于Smith预估器的模糊PID控制器(简称新型控制器);通过模拟模型参数不稳定,分别使用阶跃响应曲线和司机实操速度曲线进行仿真,对比传统的PID控制器、模糊PID控制器与新型控制器的控制效果。结果表明:新型控制器适应能力更强,速度跟踪效果和停车精度都更高。

Monitor automatic gauge control strategy with a Smith predictor for steel strip rolling

The simplified transfer function diagram block for a monitor automatic gauge control （Mon-AGC） system of strip steel rolling process was investigated. The new notion of strip sample length was given. In this way, the delay time varying with the rolling speed was evaded. After a Smith predictor was used to monitor the AGC system, the control laws were deduced for both proportional and integral regulators. The control strategies showed that by choosing the controller parameter P=∞ for both control algo- rithms each regulator could compensate the whole strip gage error in the first control step. The result shows that the integral algo- rithm is more controllable for the system regulating process and has a better steady-state precision than the proportional regulator. Compared with the traditional control strategy, the new control laws have a faster response speed and a hieher steadv-state precision.

Application of Smith Predictor Based on Single Neural Network in Cold Rolling Shape Control

Flatness is one of the most important criterion factors to evaluate the quality of the steel strip. To improve the strip＇ s flatness quality, the most frequently used methodology is to employ the closed-loop automatic shape control system. However, in the shape control system, the shape-meter is always installed at the down way of the exit of the cold rolling mill and can not sense the changes of the strip flatness in the rolling gap directly. This kind of installation results in the delay of the feedback in the control system. Therefore, the stability and response performance of the system are strongly affected by the delay. At present, there is still no mature way to design controllers for systems with time delay. Although the conventional PID controller used in most practical applications has the capability to compensate the delay, the effect of the compensation is limited, especially for the systems with long time delay. Smith predictor, as a compensator for solving this problem, is now widely used in industry systems. However, the request of highly precise model of the system and the poor adaptive performance to the changes of related parameters limit the application of the Smith predictor in practice. In order to overcome the drawbacks of the Smith predictor, a new Smith predictor based on single neural network PID （SNN-PID） is proposed. Because the single neural network is employed into the Smith predictor to improve the controller＇s self-adaptability, the adaptive capability to the varying parameters of the system is improved. Meanwhile, for the purpose of solving the problems such as time-consuming and complicated calculation of the neural networks in real time, the learning coefficient of neural network is divided into several stages as usually done in expert control system. Therefore, the control system can obtain fast response due to the improved calculation speed of the neural networks. In order to validate the performance of the proposed controller, the experiment is conducted on the shape control system in a 300 mm four-high reversing cold rolling mill. The experimental results show that the SNN-PID with Smith predictor controller can effectively compensate the delay effects and achieve better control performance than the conventional PID controller.

Smith预测器在热工自动控制系统中的应用分析

现代锅炉过热器需要在高温高压的环境中工作,锅炉在出口位置过热或者蒸汽温度较高对电厂安全运行具有重要影响。针对延迟、惯性、时变性等问题,火电厂一般选择常规的过热气温控制系统对温度进行控制,尤其是PID控制方式,但是此类控制方式容易造成鲁棒性,整体控制效果不好,容易出现各类问题。基于此,在热工自动控制系统中应用Smith预测器,可以有效解决各种问题,确保热工系统可以实现自动控制的目标。

Smith预估模糊PID控制算法及其在粉末定量称重中的应用

针对上海科源电子科技有限公司研发的定量称重系统(由高精度抖粉装置与万分之一天平组成),在工作中因粉末密度、粉末流动性、颗粒大小、湿度、天平延时等因素造成的非线性和滞后等问题,采用Smith预估模糊PID控制器优化控制方法。首先通过理论分析,得出系统的传递函数,再构建Smith预估的模糊PID控制器,以适应系统的非线性、滞后等特性,最后将此算法代入MATLAB进行仿真并于实际系统中进行1 g定量抖粉实验。Smith预估模糊PID控制算法和传统PID算法的标准差分别为0.0020和0.0042,表明Smith预估模糊PID控制算法在实际环境中稳定性更好,能有效减小系统的称重误差。

Smith预估补偿与积分分离PID在供热控制系统中的应用

针对供热控制系统时延性较大、传统PID策略控制精度不高、易产生超调与静态误差等问题,提出了一种史密斯(Smith)预估补偿与积分分离PID相结合的供热系统控制策略。首先,设计了供水温度控制系统的Smith预估补偿器,以降低热惰性因素对控制性能的影响;其次,给出了积分分离策略,用于消除静态误差;最后,将Smith预估补偿器与积分分离PID在PLC控制系统中进行部署调试,并进行实践研究。实践证明,Smith预估补偿与积分分离PID相结合的控制策略能最大限度地减弱大时延对供热系统的影响,有效提升系统的控制精度与控制性能。

Unified Smith Predictor Based H_∞ Wide-Area Damping Controller to Improve the Control Resiliency to Communication Failure

Inter-area low frequency oscillation in power system is one of the major problems for bulk power transmission through weak tie lines.Use of wide-area signal is more effective than the local area signal in damping out the inter-area oscillations.Wide area measurement system(WAMS)is convenient to transmit the wide area signal through the communication channel to the remote location.Communication failure is one of the disastrous phenomena in a communication channel.In this paper,a dual input single output(DISO)Hm controller is designed to build the control resiliency by employing two highest observability ranking wide area signals with respect to the critical damping inter-area mode.The proposed controller can provide sufficient damping to the system and also the system remains stabilized if one of the wide-area signals is lost.The time delay is an unwanted phenomenon that degrades the performance of the controllers.The unified Smith predictor approach is used to design a Hm controller to handle the time delay.Kundur's two-area and IEEE-39 bus test systems are considered to verify the effectiveness of the proposed controller.From the simulation results,it is verified that,the proposed controller provides excellent damping performance at normal communication and improves the controller resiliency to counteract the communication failure.

Robust tuning method for modified smith predictor

A robust tuning method for ο^Astroem＇s two-degree of Freedom Modified Smith Predictor （MSP） is proposed, and it can achieve the fast setpoint and load disturbance responses independently. The tuning rules may meet the requirements within a certain delay margin according to the robustness theory. The simulation results illustrate that the tuning method is efficient compared with other controllers. Finally, the MSP controller is applied to the 15L batch fermentation system for controlling the temperature in bioreactor, and the experiment results further verify that the robust tuning rules may achieve good performance.

自适应Fuzzy-Smith-PID控制器在加热炉温度控制中的研究与仿真

以箱式加热炉为研究对象,针对PID控制在温度控制中存在滞后和时变性的缺陷,提出一种带有Smith补偿环节的新型模糊PID控制方案,利用MATLAB实现仿真。由仿真结果可知,相比Smith控制和模糊控制,改进后的系统精度更高,抗干扰性和鲁棒性增强,系统过渡过程较为平稳,整体控制效果理想,具有良好的推广价值。

基于BRGWO算法和滤波Smith预估器的气弹系统时滞控制

气弹控制系统的驱动器、闭环信号回路在实际中会存在时滞环节,由于气弹敏感性和环境复杂性,时滞会引起控制信号迟延并导致气弹控制极速恶化、甚至造成系统失稳,该问题以往研究较少。针对翼型时滞气弹控制问题,设计了一种基于BRGWO算法和改进型滤波Smith的最优气弹控制方法。首先,引入二阶滤波器改进Smith预估器,设计了翼型气弹控制器;然后,创新设计了一种双向随机灰狼优化算法(bidirectional random grey wolf optimization, BGWO),提高了时滞下气弹控制参数的全局寻优能力,该算法改进了不同等级灰狼的狩猎策略,提高跳出非理想值机率、避免陷入局部最优。利用最小增益原理,在理论上证明了闭环系统稳定性。仿真结果表明,对比传统智能优化算法(如遗传算法、灰狼优化算法)和多种已有控制器(经典Smith、PI-PD型Smith和传统滤波Smith预估器),该方法具有更强的时滞补偿能力和更优的气弹控制性能,在不确定时滞、不确定风速、刚度变化和驱动干扰等算例下,保持了优良的时滞气弹控制效果,具有较强的鲁棒性。

垃圾渗滤液污水处理设备的臭氧投加复合抗扰控制

垃圾渗滤液污水处理设备中的臭氧投加系统具有大时滞、大惯性和多扰动的特点,导致难以实时调整臭氧投加量,从而影响后续设备出水水质。针对以上问题,在水流量比例的控制方面提出一种基于扰动观测器的改进型Smith预估器与滑模控制相结合的复合抗扰控制。其中,滑模控制为主控制器,扰动观测器用于估计出系统的集总扰动并反馈至前向通道消除扰动的不利影响,以便于Smith预估器更好地进行时滞补偿。仿真和实验结果表明,复合抗扰控制相较于PID控制和自抗扰控制具有更好的控制性能和抑制扰动的能力,能够有效提高垃圾渗滤液污水处理设备的出水水质。

基于Smith预估模糊PID的氨法脱硫控制策略

氨法脱硫系统存在滞后大、非线性和实时负荷跟踪性差等问题。针对该问题设计的Smith预估控制器通过补偿延迟时间提高了系统的实时性。但通常采用试凑法来设定系统中的PID(Proportion Integral Differential)参数,导致系统稳定性较差。文中提出模糊PID参数自适应整定控制方法,通过模糊控制器求得PID的3个参数的调整值,自适应地调整PID参数,将SNO_(x)的浓度控制在预设值附近。与传统阶跃信号判断控制效果不同,文中所提方法以实时的负荷数据来进行模型仿真,数据仿真结果也证明了Smith预估模糊PID控制器的可行性。系统稳定时SNO_(x)浓度与预设值的误差在0.5 ppm以内,缩短了调节时间,表明所提方法改善了氨法脱硫控制系统的实时跟踪性,实现了快准稳的脱硫控制性能。

基于粒子群优化算法的太阳能水培智能控制系统设计与实现

为实现水培营养液水质参数的高效、精确控制,减少设备供能产生的碳排量,构建了一个基于粒子群优化(Particle Swarm Optimization,PSO)算法和最大功率点跟踪(Maximum Power Point Tracking,MPPT)算法的水培智能控制系统。用PSO算法优化模糊控制器的量化、比例因子,加入Smith预估器补偿反馈时延,对pH为4.5、电导率(Electrical Conductivity,EC)为0 mS/cm的营养液进行精确调控。经过优化,分别在44 s和43 s后达到预设值,并能维持稳定状态。建立光伏发电模块,引入MPPT算法,缩短跟踪时长至0.04 s。结果表明,该系统能提高营养液水质参数的调节精度,缩短控制时长,增强水培环境的稳定性;同时,能提升发电效率,实现节能减排。

基于增强型扩张状态观测器的永磁同步电机低抖振高抗扰二阶终端滑模电流控制

永磁同步电机电流滑模控制具有较好的参数鲁棒性,但控制精度受到滑模抖振的影响,且抖振抑制与抗扰性之间存在矛盾。为此,该文提出一种基于增强型扩张状态观测器的二阶终端滑模电流控制方案,可以有效提升电流控制性能。通过二阶终端滑模控制器的设计,将一阶积分快速终端滑模嵌套在二阶非奇异终端滑模面中,使得滑模抖振得到较好的抑制,同时实现电流无稳态误差的快速收敛。通过引入扩张状态观测器对扰动信号的集总估计与补偿,缓解了抖振与抗扰性之间的矛盾,进一步提升了电流精度。针对数字控制的延迟影响,设计了Smith预估器,提升了扰动补偿精度。最后,通过实验对该文所设计的电流控制方案进行验证,并通过对比展示了该方案的有效性。

Smith预估控制研究进展

Smith预估控制能够有效克服系统时延,在过程工业中有着广泛应用。然而这种控制方法对系统建模精度要求很高,当出现系统不确定性和外部干扰时,Smith预估控制性能会显著降低。本文对Smith预估控制器进行了简单介绍,并对Smith预估控制器结构改进的研究、参数整定方法的研究和与高级控制算法结合的研究等进行了介绍和总结。

模糊Smith智能温度控制器的设计与仿真

结合模糊PID控制与模糊自适应Smith预估控制的优点,提出了模糊Smith智能控制方法。用模糊控制方法设计了改进型Smith预估器的滤波时间常数,并制定了其整定规则和参数的模糊自适应调整机构。仿真研究表明,模糊Smith智能控制能改善参数时变的纯滞后系统的控制性能,提高系统控制时的鲁棒性与自适应性。

基于Smith预估器的换热器温度控制系统的研究

针对换热器温度控制系统的大时滞问题,提出了一种Smith预估控制器的设计方法,并由MCS51微机系统实现。认为该方法能有效克服大纯滞后对控制系统稳定性的影响。计算机仿真与实验研究表明,其控制效果明显优于常规PID控制,非常适用于换热器的温度控制。

基于Smith预估器的PCR仪时滞温控系统

为了解决聚合酶链式反应(PCR)仪温度控制中的纯滞后问题,在试验数据的基础上,基于Matlab搭建仿真模型.仿真结果表明,加入Smith预估补偿环节可以较好地解决纯滞后效应带来的积分累积问题.将仿真得到的方法移植到实际的控制中,可获得良好的控制效果.最后提出添加一个比例-积分-微分(PID)控制器的改进算法,用以解决Smith预估控制算法中鲁棒性不强的问题.

气动人工肌肉手臂的神经网络Smith预估控制

针对含时滞d的1关节气动人工肌肉(PAM)手臂,用三层递归神经网络(RNN),建立PAM手臂包含时滞的模型(即非线性Smith预估器),并超前d步预测PAM手臂的输出角度。将此超前d步的预测值作为反馈量,与设定值相比较得到的误差作为PID控制器输入量,实现Smith预估PID控制。同时每一步都用RNN模型当前时刻的输出值与PAM手臂当前时刻实际输出值之差的平方做为RNN权值的在线调整准则对RNN预测模型的权值进行在线调整,以自适应PAM手臂的不确定性和时变性。使用Matlab通过串口和研华亚当模块对实物PAM手臂进行控制,控制效果表明所提出的Smith预估PID控制算法比常规PID控制算法的性能有显著提高,证明所提出的算法是有效的和切实可行的。

自适应Smith预估极点配置自效正PI控制器

对具有大惯性、大纯时延、变参数的过程控制对象，提出了一种带有自适应Ｓｍｉｔｈ预估的极点配置的自效正ＰＩ控制方案，以１０ｔ／ｈ链条炉作为控制对象，通过数字仿真，并与常规 ＰＩ比较，证明了该方案比常规ＰＩ有更好的控制性能。