自适应PID控制器实现熟料料层自动控制

本文针对传统PID控制器在冷却机应用中存在的问题,提出了一种自适应PID控制器实现冷却机熟料料层的自动控制。在给出冷却机高温熟料料层厚度的测量方法之后,提出了模糊控制策略和PID控制器参数整定表。     

PID controller tuning for a multivariable glass furnace process by genetic algorithm

Standard genetic algorithms (SGAs) are investigated to optimise discrete-time proportional-integral-derivative (PID) controller parameters, by three tuning approaches, for a multivariable glass furnace process with loop interaction. Initially, standard genetic algorithms (SGAs) are used to identify control oriented models of the plant which are subsequently used for controller optimisation. An individual tuning approach without loop interaction is considered first to categorise the genetic operators, cost functions and improve searching boundaries to attain the desired performance criteria. The second tuning approach considers controller parameters optimisation with loop interaction and individual cost functions. While, the third tuning approach utilises a modified cost function which includes the total effect of both controlled variables, glass temperature and excess oxygen. This modified cost function is shown to exhibit improved control robustness and disturbance rejection under loop interaction.     

模糊自整定PID控制在聚合反应中的研究

针对工业生产中常用的反应釜,提出利用模糊自整定PID控制器实现聚合反应温度控制的方法,实现PID控制器参数在线自调整,提高PID控制器的性能和系统的精度.仿真结果表明,该模糊自整定PID对被控系统的适应性强、鲁棒性好、超调小、反应时间快,能很好地适应现实生产过程中的控制要求.     

A hybrid intelligent system for PID controller using in a steel rolling process

With the aim to improve the steel rolling process performance, this research presents a novel hybrid system for selecting the best parameters for tuning in open loop a PID controller. The novel hybrid system combines rule based system and Artificial Neural Networks. With the rule based system, it is modeled the existing knowledge of the PID controller tuning in open loop and, with Artificial Neural Network, it is completed the rule based model that allow to choose the optimal parameters for the controller. This hybrid model is tested with a long dataset to obtain the best fitness. Finally, the novel research is validated on a real steeling roll process applying the hybrid model to tune a PID controller which set the input speed in each of the gearboxes of the process.     

PID controller design for robust performance

This note is devoted to the problem of synthesizing proportional-integral-derivative (PID) controllers for robust performance for a given single-input-single-output plant in the presence of uncertainty. First, the problem of robust performance design is converted into simultaneous stabilization of a complex polynomial family. An extension of the results on PID stabilization is then used to devise a linear programming design procedure for determining all admissible PID gain settings. The most important feature of the proposed approach is that it computationally characterizes the entire set of the admissible PID gain values for an arbitrary plant.     

Stabilization and algorithm of integrator plus dead-time process using PID controller

In this paper, we develop an algorithm to determine the entire set of stabilising PID parameters for the integrator plus dead-time process. Our method is a combination of the traditional D-partition technique and graphical technique. We first apply the D-partition technique to address the stability regions in the plane of proportional and integral gains, which depend on the steady-state gain and the time delay. Next for fixed proportional gain, again using the D-partition technique we obtain a series of critical straight lines in the plane of integral and derivative gains and then choosing the derivative gain as a parameter, we investigate how the derivative gain affects the distribution of the roots of the corresponding characteristic equation of the closed-loop control system, which provide the stability regions in the plane of integral and derivative gains. On the base of the results obtained in the previous two steps, an efficient algorithm for determining the entire set of stabilising PID parameters is also proposed. Finally, numerical simulations are given to support our theoretical results.     

Gain-scheduled PID controller design

Gain scheduling (GS) is one of the most popular approaches to nonlinear control design and it is known that GS controllers have a better performance than robust ones. Following the terminology of control engineering, linear parameter-varying (LPV) systems are time-varying plants whose state space matrices are fixed functions of some vector of varying parameters. Our approach is based on considering that the LPV system, scheduling parameters and their derivatives with respect to time lie in a priori given hyper rectangles. To guarantee the performance we use the notion of guaranteed costs. The class of control structure includes centralized, decentralized fixed order output feedbacks like PID controller. Numerical examples illustrate the effectiveness of the proposed approach.     

Robust self-tuning PID controller for nonlinear systems

In this paper, we propose a robust self-tuning PID controller suitable for nonlinear systems. The control system employs a preload relay (P_Relay) in series with a PID controller. The P_Relay ensures a high gain to yield a robust performance. However, it also incurs a chattering phenomenon. In this paper, instead of viewing the chattering as an undesirable yet inevitable feature, we use it as a naturally occurring signal for tuning and re-tuning the PID controller as the operating regime digresses. No other explicit input signal is required. Once the PID controller is tuned for a particular operating point, the relay may be disabled and chattering ceases correspondingly. However, it is invoked when there is a change in setpoint to another operating regime. In this way, the approach is also applicable to time-varying systems as the PID tuning can be continuous, based on the latest set of chattering characteristics. Analysis is provided on the stability properties of the control scheme. Simulation results for the level control of fluid in a spherical tank using the scheme are also presented.     

PID控制器的性能监控与评估

为了解决目前工业系统中普遍使用的PID控制器由于工况变化等原因引起的系统发生时变而导致所在回路PID控制器性能可能下降的问题,本文提出了一种专门针对PID控制器进行性能评估、优化及监控的方法,即:PID循环评估优化算法。该算法利用系统闭环输入输出数据,使用基于MVC(minimum variance control)的PID最小方差准则,来对PID控制器的性能进行评估,并且计算出在最小方差意义下最优PID控制器参数;评估过程结果与现实系统输出方差进行比较,做为PID参数在线优化的判断依据,当现实系统性能低于某一标准的时候对控制器进行优化处理。在整个算法中,通过输入输出数据的处理与判断,利用评估优化后的PID参数对系统进行控制,并再次回到最初的输入输出数据的处理和判断过程,实现在控制过程中的系统性能监控。本文的计算机仿真试验验证了该方法的有效性,由图可看出,系统发生渐变和突变后,当输出方差超过了程序限定的标准时,在1 300秒内系统能自动评估并施行优化而达到稳定。该循环评估优化算法现实了在对系统进行性能评估监控的同时,能按照一定条件作为标准对系统的PID参数进行优化,最终使得系统具有自我监控评估和自我优化的能力...     

Stabilization of control loops consisting of FOPDT process and parameter-dependent PID controller

In this paper, problem of stability analysis of the control loops consisting of first-order plus dead time (FOPDT) processes and proportional-integrative-derivative (PID) controllers is studied, where the controller coefficients are functions of one or more independent parameters. An effective procedure is presented to determine a stability region in the independent parameters space. This method does not require complex numerical calculations such as solving nonlinear equations. It is based on usage of a two-valued indicator function and by using that, a stability region is easily determined. In order to clarify that, why the stability region needs to be specified in the “independent parameters space” an optimal method is given to design the PID controller for the FOPDT processes, as an instance. In this optimal method the controller coefficients are obtained as the functions of a free parameter, where this parameter needs to be chosen by the designer such that it should be near to the maximum operating frequency of the system, besides on the other hand the closed-loop system to be stable. In the end, two illustrative examples are given in order to show the usefulness and effectiveness of the proposed method, and to compare the obtained stability regions with the whole stability regions.     

矿井通风机倒机过程自适应PID抗饱和控制器设计

针对矿井通风机倒机过程中存在的执行器饱和问题,将变结构PID抗饱和控制与非线性自适应控制相结合,设计了自适应PID抗饱和控制器。基于带死区的投影算法建立矿井通风机倒机过程线性和非线性模型;针对这2个模型,分别设计一个变结构PID抗饱和控制器;计算线性和非线性自适应PID抗饱和控制器在不同状态下的运行评价指标,选择评价指标值较小的控制器用于该状态下的矿井通风机倒机过程控制。仿真结果表明,自适应PID抗饱和控制器能够保证井下传输风量的平稳,很好地解决了执行器饱和问题。     

数控机床位置伺服系统新型变结构控制器的设计

介绍了数控机床位置伺服系统新型变结构控制器的设计。仿真结果表明，该变结构控制器能在不影响系统性能的情况下有效地消除抖动现象。     

Self-tuning PID/I controller

A self-tuning controller based on the method of frequency identification and intended for controlling plants with time-varying parameters under arbitrary bounded exogenous disturbances was proposed. The impact of the harmonic frequencies of the test signal on the results of identification over a prescribed time was studied. Methods to choose frequencies and an algorithm to adjust the amplitudes of the harmonics of the test signal were proposed. The duration of the identification parameters of the plant model is determined automatically depending on the intensity of the exogenous disturbance and the desired relative accuracy of identification. The results of experimental studies of the proposed controller demonstrating its efficiency were presented.     

Experimental comparison of PID vs. PID plus nonlinear controller for subsea robots

This paper presents a new approach for designing simple nonlinear robust controllers for underwater vehicles. The paper presents several in-water experiments performed on the VORTEX vehicle developed by IFREMER. We first introduce some general modeling considerations of underwater vehicles, then we present the VORTEX dynamic model and some of the special features of the VORTEX vehicle that are important for control. Among these, low sampling rates for sensor and actuator nonlinearities are considered. The main aim of this paper is to experimentally investigate the benefits of adding an easy-to-tune nonlinear control loop to the actual linear compensator in order to improve the stability and the disturbance rejection properties of the closed-loop system. The advantage of this method is two-fold. First the additional nonlinear loop does not modify the original linear (PID) regulator. Second the design of this additional loop does not rely on the system model and is simple to tune. The results presented in this paper were obtained using the VORTEX vehicle both in simulation and during real experiments; they demonstrate the advantages of using a PID with this nonlinear loop over a simple PID control.     

高阶时滞过程预测PID控制器设计及鲁棒稳定性分析

针对高阶加滞后对象稳定性分析的局限性,提出了预测PID控制器的设计方法,利用Kharitonov定理和边缘理论分析此系统在参数不确定情况下输入、输出的鲁棒稳定性,并给出了系统保持稳定的最大过程参数区间。仿真结果表明,当过程参数偏离标称值时,此类预测PID控制器的设计方法能够使系统保持很好的控制性能和鲁棒稳定性能。是一种值得在实际工程中推广应用的新型控制器。     

多扰动动态下的PID控制器性能评价

对多扰动动态下PID控制器的性能评价进行了研究。当系统具有多个扰动动态时，PID控制器并不能使对多个扰动动态的控制性能都达到最佳，此时需根据对各扰动的重视程度来折中选择对其的控制性能。为了对此情况下系统的控制性能进行评价，文中构造了一种带加权的综合性能评价函数，其权值与对各扰动的重视程度相对应。通过选取适当的权值并对综合性能评价函数求最优，得到了系统对各扰动动态的最佳折中控制性能。以此最佳折中控制性能作为参照基准与系统实际性能相对比，实现了上述性能评价的目的。仿真例子表明了该方法的有效性。     

A fuzzy PID controller for nonlinear and uncertain systems

 In order to control systems that contain nonlinearities or uncertainties, control strategies must deal with the effects of these. Since most control methods based on mathematical models have been mainly focused on stability robustness against nonlinearities or uncertainties, they are limited in their ability to improve the transient responses. In this paper, a nonlinear fuzzy PID control method is suggested, which can stably improve the transient responses of systems disturbed by nonlinearities or unknown mathematical characteristics. Although the derivation of the control law is based on the design procedure for general fuzzy logic controllers, the resultant control algorithm has analytical form with time varying PID gains rather than linguistic form. This means the implementation of the proposed method can be easily and effectively applied to real-time control situations. Control simulations are carried out to evaluate the transient performance of the suggested method through example systems, by comparing its responses with those of the nonlinear fuzzy PI control method developed in [9].     

A new design for a PID plus feedforward controller

In this paper, a new design and tuning procedure for a PID plus feedforward controller is proposed. It consists of determining a feedforward signal in order to achieve a predefined process output transition time assuming a first order plus dead time model of the process. Then, the PID parameters are tuned by any conventional method in order to assure a good load disturbance rejection and the reference signal to the closed-loop system is obtained by filtering appropriately the set-point step signal. Simulation and experimental results show that the method outperforms the typical (inverse) model-based approach despite its simplicity and it is therefore suitable to implement in Distributed Control Systems as well as in single-station controllers.     

基于二次型优化的单神经元PID控制器及其pH过程控制应用

针对pH值控制这种强非线性过程,提出基于二次型优化的单神经元PID学习算法,该算法不用考虑常规PID对非线性过程分段区间划分的问题。基于这种算法的PID控制器解决了普通单神经元PID控制器静态性能不佳的问题。仿真结果表明,这种改进型控制算法比原算法具有更好的自适应能力和抗干扰性能。