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1.
The method of identifying first order plus time delay transfer function model proposed for unstable systems by Ananth and Chidambaram [Closed loop identification to transfer function model for unstable systems, J. Franklin Inst. 336 (1999) 1055-1061] is modified to avoid the stability problems [Cheres, Parameter estimation of an unstable system with a PID controller in a closed loop configuration, J. Franklin Inst., 2005, accepted for publication] of the method. Two modifications are proposed. In the first modification of the method, the under-determined algebraic equations problem is converted into an optimization problem for calculation of the three parameters of the first order plus time delay (FOPTD) model. A simple method is given for the initial guess values of the model parameters. In the second approach, from the definition of Laplace transform of the output response, a third equation is formulated. The resulted three equations, in terms of the three parameters of the transfer function model, are then numerically solved. Simulation results are given for the second order plus time delay transfer function considered by Cheres 2005 [Parameter estimation of an unstable system with a PID controller in a closed loop configuration, J. Franklin Inst., 2005, accepted for publication]. The responses of the identified models with the same PID controllers are compared with that of the actual system. PID controllers are designed based on the identified models. The closed loop responses of the controllers on the original system are evaluated and compared. The present methods give better control performances.  相似文献   

2.
电厂主汽温被控对象是一个大惯性、大迟延、非线性且对象变化的系统,基于BP神经网络的PID控制,利用神经网络的自学习、非线性和不依赖模型等特性实现PID参数的在线自整定,充分利用PID和神经网络的优点。用一个多层前向神经网络,采用反向传播算法,依据控制要求实时输出Kp、Ki、Kd,依次作为PID控制器的实时参数,代替传统PID参数靠经验的人工整定和工程整定,以达到对大迟延主汽温系统的良好控制。对这样一个系统在MATLAB平台上进行仿真研究,仿真结果表明基于BP神经网络的自整定PID控制具有良好的自适应能力和自学习能力,对大迟延和变对象的系统可取得良好的控制效果。  相似文献   

3.
经典PID控制应用广泛,但由于其参数的工程整定方法一般为试探法,这样对于设计人员的调试经验要求较高。随着工程技术的发展,被控对象也越来越复杂,经典PID参数整定也变得复杂,本文提出了一种基于遗传算法优化的PID控制器,PID的参数不仅可以自动整定而且支持在线整定。  相似文献   

4.
Using the direct synthesis method, a PID controller in series with a lead/lag compensator is designed for control of open loop integrating processes with time delay. Set-point weighting is considered for reducing the undesirable overshoot. Guidelines are provided for selection of the desired closed loop tuning parameter in the direct synthesis method and set point weighting parameter. The method gives significant load disturbance rejection performances. Illustrative examples are considered to show the performances of the proposed method. Significant improvement is obtained when compared to recently reported methods.  相似文献   

5.
针对纯滞后、非线性、时变的胶黏剂生产过程,引入迭代学习控制方法,对反应液温度进行控制。仿真结果表明：与PID控制方法相比,迭代学习PID控制性能更好。  相似文献   

6.
This paper is concerned with stability analysis and stabilization of time-varying delay discrete-time systems in Lyapunov-Krasovskii stability analysis framework. In this regard, a less conservative approach is introduced based on non-monotonic Lyapunov-Krasovskii (NMLK) technique. The proposed method derives time-varying delay dependent stability conditions based on Lyapunov-Krasovskii functional (LKF), which are in the form of linear matrix inequalities (LMI). Also, a PID controller designing algorithm is extracted based on obtained NMLK stability condition. The stability of the closed loop system is guaranteed using the designed controller. Another property that is important along with the stability, is the optimality of the controller. Thus, an optimal PID designing technique is introduced in this article. The proposed method can be used to design optimal PID controller for unstable multi-input multi-output time-varying delay discrete-time systems. The proposed stability and stabilization conditions are less conservative due to the use of non-monotonic decreasing technique. The novelty of the paper comes from the consideration of non-monotonic approach for stability analysis of time-varying delay discrete-time systems and using obtained stability conditions for designing PID controller. Numerical examples and simulations are given to evaluate the theoretical results and illustrate its effectiveness compared to the existing methods.  相似文献   

7.
In the realm of flight control, proportional–integral–derivative (PID) control is still widely used in practice due to its simple structure and efficiency. The robustness and dynamic performance of PID controller can be evaluated by stability margins. Based on the empirical knowledge about the unstable flight dynamics, the analytical tuning formulas of the PID pitch attitude control with actuator delay are derived with the help of several proper approximations. These tuning formulas can meet the increasing gain and phase margins (iGPM) requirement and avoid time-consuming trial-and-error tuning process. The feasible iGPM area is established in 2-D plane subject to several conditions, especially taking the decreasing gain margin into account, wherein the numerical polynomial solving approaches are employed. The relationship between an existing PD tuning scheme and the proposed PID tuning method is also revealed. The applicable area of the tuning rule is then investigated on the basis of a crucial assumption. Furthermore, the achievable decreasing gain and phase margins (dGPM) area is obtained when the decreasing gain margin is critical; and another tuning rule is derived according to the dGPM specifications. The effect of the actuator delay on the achievable GPM area is demonstrated in a straightforward manner such that the reasonable criteria can be specified. Finally two numerical paradigms are presented to validate the proposed method; and the robustness and dynamic performance of the PID control are also reexamined for unstable flight dynamics.  相似文献   

8.
预测函数控制在球磨机磨矿回路中的应用   总被引：2，自引：0，他引：2  
球磨机磨矿回路具有多变量强耦合、大延迟和非线性等特性,生产工况变化性大.常规采用多回路PID解耦控制.使回路之间的相互耦合作用减到最小,但这种控制不能及时且精确地控制磨矿过程.模型预测控制能够解决多变量系统之间的耦合作用,而预测函数控制是在模型预测控制原理的基础上提出的,并且将控制规律进行了结构化设计,使控制器在线计算量小,参数调整简单,跟踪快速,具有很强的抗扰动性和鲁棒性.本文以实验型球磨机磨矿回路为研究对象,分别设计多回路PID解耦控制和预测函数控制,并对两种控制的仿真效果进行对比.仿真结果表明,该控制策略具有较好的跟踪性能、抗干扰能力,可以达到较为理想的控制效果.  相似文献   

9.
Gas flow has fractional order dynamics; therefore, it is reasonable to assume that the pneumatic systems with a proportional valve to regulate gas flow have fractional order dynamics as well. There is a hypothesis that the fractional order control has better control performance for this inherent fractional order system, although the model used for fractional controller design is integer order. To test this hypothesis, a fractional order sliding mode controller is proposed to control the pneumatic position servo system, which is based on the exponential reaching law. In this method, the fractional order derivative is introduced into the sliding mode surface. The stability of the controller is proven using Lyapunov theorem. Since the pressure sensor is not required, the control system configuration is simple and inexpensive. The experimental results presented indicate the proposed method has better control performance than the fractional order proportional integral derivative (FPID) controller and some conventional integral order control methods. Points to be noticed here are that the fractional order sliding mode control is superior to the integral order sliding mode counterpart, and the FPID is superior to the corresponding integral order PID, both with optimal parameters. Among all the methods compared, the proposed method achieves the highest tracking accuracy. Moreover, the proposed controller has less chattering in the manipulated variable, the energy consumption of the controller is therefore substantially reduced.  相似文献   

10.
In the electric driving system, the measurement of the motor speed error becomes more and more important, which has an impact on the system vibration suppression. In this paper, based on the single-neuron adaptive PID control method, the dual-inertia system considering gear friction torque is modeled and studied. Firstly, the dual-inertia system with gear friction is established, and dynamic differential equations of it are derived; Then, the comprehensive meshing stiffness and the time-varying friction torque of the gear system are deduced; Next, the Ziegler-Nichlos frequency domain response method is adopted to obtain the parameters of the PID controller. The control methods including the PID, Fuzzy-PID with DOB and single-neuron adaptive PID are utilized to adjust the motor speed of the system; Finally, the effects of gear friction, the moment of inertia of load and control methods on motor speed and system error are analyzed.  相似文献   

11.
王旭  姜晓伟 《中国科技信息》2012,(1):108-109,111
制药工业是我国国民经济的主要产业,药品生产质量的要求也越来越严格.药品生产车间洁净区的环境条件是影响药品生产质量的主要因素之一,针对药品生产车间温度控制系统大滞后、大惯性、非线性,以及难以建立精确的数学模型等特点。在传统PID控制的基础上,基于神经网络具有任意非线形表达能力,以及可以通过对系统性能的学习来实现P I D参数的在线调整,确定最佳组合的P I D参数来实现车间温度的有效控制,本文通过仿真分析表明控制效果良好,具有调节时间短、无超调、稳态误差小等优点。  相似文献   

12.
This paper presents a tuning approach based on a tabu search algorithm (TSA) to obtain the optimal proportional-integral-derivative (PID) controller parameters in order to achieve a desired transient response. TSA is used to determine the main parameters of the PID controller. The performance of the PID controlled system is examined by considering the characteristics of the step response of the plant. Simulation results demonstrate that the tabu algorithm based approach is one of the useful methods for PID controller tuning, and using by the presented method, performance of the controlled system can be significantly improved according to the given control specifications.  相似文献   

13.
The control of a multirate sampled-data, stirred-tank chemical reactor system using a parameter plane method is considered. Due to wide acceptance of proportional-plus- integral-plus-derivative (PID) control in the chemical process industries, a PID controller with a “slow-fast” multirate scheme is used for the chemical reactor system. Based on two related stability equations and using the PID gains as the adjustable parameters, the set of all possible PID gains to maintain the chemical reactor system's stability, and at the same time, to ensure the system has a specified gain margin, phase margin, damping ratio and damping factor is determined. The effects of changing the integer N (which is the ratio of the sampling rates between a slow-and a fast-sampler) and the basic sampling period T on the set of PID gains are examined and the results for single-rate and multirate cases are also studied.  相似文献   

14.
文中将Labview的功能融入到传统的PID控制算法中,提出了几种改进PID控制算法性能的方法。在PID现有实现方式的基础上,通过这些方法来修改算法,解决了PID控制算法的缺点,提高了PID控制器的性能。  相似文献   

15.
This paper discusses PID controller tuning for integrating processes with varying time-delays. Most of the existing tuning rules for the first-order lag plus integrator plus delay (FOLIPD) processes that we mainly focus on have the same general structure, and the properties of these rules are discussed in conjunction with varying time-delays. The analysis leads to novel tuning rules, where the maximum amplitude of an arbitrarily varying time-delay can be given as a parameter, which makes the use of the rules attractive in several applications. We will also extend the analysis to integrating processes with second-order lag and apply the design guidelines for a networked control application. In addition, we propose a novel tuning method that optimizes the closed-loop performance with respect to certain robustness constraints while also providing robustness to delay variance via jitter margin maximization. Further, we develop new PID controller tuning rules for a wide range of processes based on the proposed method. The new tuning rules are discussed in detail and compared with some of the recently published results. The work was originally motivated by the need for robust but simultaneously well-performing PID parameters in an agricultural machine case process. We also demonstrate the superiority of the proposed tuning rules in the case process.  相似文献   

16.
阐述了单片机通过PID和PWM技术实现对角度传感器的控制过程和编程要点,给出了系统的组成框图,分析了单片机实现PWM控制技术的设计方法和PID算法原理,并给出了由PWM信号驱动直流电机的一般设计方法。  相似文献   

17.
挖掘机液压系统控制系统是一个大滞后、非线性系统,难于建立精确的数学模型,应用常规PID控制不能达到理想的控制效果。模糊PID控制是智能控制技术的一类,是解决复杂非线性对象控制问题的一个有效途径。所以,在液压控制系统中采用模糊PID控制器,使系统有较好的鲁棒性、控制精度及动态性能。模糊控制器采用8751单片机的软硬件实现,运行结果证明了这种控制方案的可行性。  相似文献   

18.
A novel direct synthesis (DS) method for simultaneous and non-iterative design of multi-loop PID controllers for stable multivariable processes is presented in this article. We deal with the specifications of the desired closed-loop dynamics, which is a critical design decision in the DS method, for designing multi-loop controllers. Control loop interactions in multi-loop control systems are usually undesirable but unavoidable due to inter-channel interactions of multivariable processes. The main feature of the method is that the multi-loop control design aims at reducing the interactions among loops. The proposed DS method specifies the design target in terms of the frequency response of the desired closed-loop transfer function (CLTF) and synthesizes the controllers in the frequency domain. We develop an approach to effectively specify the desired closed-loop frequency response to achieve improved control performance by minimizing the sum of the magnitude of the interactive parts in the desired CLTF matrix. With the desired closed-loop frequency response and a process model, the frequency response of an ideal multi-loop controller is synthesized and then approximated to a PID controller. We provide simulation studies of three industrial benchmark processes and a nonlinear quadruple tank system to illustrate the design result and performance of the proposed method and make comparisons with several existing methods. Our results prove the effectiveness of the frequency-domain DS method. The proposed multi-loop PID controllers achieve reduced loop interactions and provide satisfactory overall performance.  相似文献   

19.
In this paper, an on-line identification and auto-tuning method is proposed for multivariable processes. Systematic identifying procedures and on-line tuning rules are developed for computing parameters of proportional plus integration and Lead compensators. The performance of the compensated systems can be evaluated by wanted bandwidth, phase margins and low-interacting characteristics. No iteration for finding parameters of compensator is needed. Parameters of PI/Lead compensator can be retuned if they are needed. Three numerical examples give the proposed method provides better performance, robustness and less interaction effects than those of other mentioned on-line computing methods.  相似文献   

20.
This paper proposes to use a hybrid Stochastic Fractal Search (SFS) and Local Unimodal Sampling (LUS) based multistage Proportional Integral Derivative (PID) controller consisting of Proportional Derivative controller with derivative Filter (PDF) plus (1 + Proportional Integral) for Automatic Generation Control (AGC) of power systems. Initially, a single area multi-source power system consisting of thermal hydro and gas power plants is considered and parameters of Integral (I) controller is optimized by Stochastic Fractal Search (SFS) algorithm. The superiority of SFS algorithm over some recently proposed approaches such as optimal control, Differential Evolution (DE) and Teaching Learning Based Optimization (TLBO) is demonstrated. To improve the system performance further, LUS is subsequently employed. The study is further extended for different controllers like PID, and proposed multistage PID controller and the superiority of multistage PID controller over conventional PID controller structure is demonstrated. The study is further extended to a two-area six unit multi-source interconnected power system and the superiority of proposed approach over, TLBO and optimal control is demonstrated. Finally the study is extended to a three unequal area system power system with appropriate nonlinearities such as Generation Rate Constraint (GRC), Governor Dead Band (GDB) and time delay. From the analysis, it is found that hybrid SFS–LUS algorithm is superior to the original SFS algorithm and substantial improvement in system performance are realized with proposed multistage PID controller over conventional PID controller structure.  相似文献   

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