Simultaneous closed-loop tuning of cascade controllers based directly on set-point step-response data

This study presents a novel closed-loop tuning method for cascade control systems, in which both primary and secondary controllers are tuned simultaneously by directly using set-point step-response data without resorting to process models. The tuning method can be applied on-line to improve the performance of existing underperforming cascade controllers by retuning controller parameters, using routine operating data. The goal of the proposed design is to obtain the parameters of two proportional-integral-derivative (PID)-type controllers, so that the resulting inner and outer loops behave as similarly as possible to the appropriately specified reference models. The tuning rule and optimization problem related to the proposed design are derived. Based on the rationale behind cascade control, the secondary controller is designed based on disturbance rejection to quickly attenuate disturbances. The primary controller is designed to accurately account for the inner-loop dynamics, without requiring an additional test. In addition, robustness considerations are included in the proposed tuning method, which enable the designer to explicitly address the trade-off between performance and robustness for inner and outer loops independently. Simulation examples show that the proposed method exhibits superior control performance compared with the previous (model-based) tuning methods, confirming the effectiveness of this novel tuning method for cascade control systems.     

基于改进遗传算法的PID控制器设计

针对一般遗传算法存在的不足，提出一种改进的遗传算法，并将其应用于PID控制器参数设计。该方法采用实数编码，是为了操作方便、提高精度和收敛速度，且能克服传统PID参数整定的费时性。仿真结果表明，基于改进遗传算法设计的PID控制器获得了良好的控制效果，其控制性能优于常规的PID控制器。     

基于模糊自整定PID的主汽温串级控制系统的设计

火电厂主汽温具有大惯性、大迟延和时变特性等特性,采用常规的PID串级控制难以获得满意的控制效果.为此,提出一种基于模糊自整定PID控制器的串级控制系统,该系统将模糊控制、PID控制和串级控制三者有机地相结合,提高了主汽温控制系统的控制品质.仿真结果表明：系统超调量、调节时间和抗干扰能力明显优于常规的PID串级控制.     

一种改进的针对线性时不变单输入单输出系统的PID控制器

本文提出了一种提高PID控制器的稳定范围和控制精度的改进方法，即通过改变PID控制器的积分项结构，并给出了二阶系统控制对象达到渐进稳定时的相关参数方程。最后采用Ziegler-Nichols参数整定法对改进后的PID控制器和常规PID控制器进行了仿真，仿真结果表明控制效果明显提高。     

An optimal adaptive robust PID controller subject to fuzzy rules and sliding modes for MIMO uncertain chaotic systems

In this paper, an optimal adaptive robust PID controller based on fuzzy rules and sliding modes is introduced to present a general scheme to control MIMO uncertain chaotic nonlinear systems. In this control scheme, the gains of the PID controller are updated by using an adaptive mechanism, fuzzy rules, the gradient search method, and the chain rule of differentiation in order to minimize the sliding surfaces of sliding mode control. More precisely, sliding mode control is used as a supervisory controller to provide sufficient control inputs and guarantee the stability of the control approach. To ascertain the parameters of the proposed controller and avoid trial and error, the multi-objective genetic algorithm is employed to augment the performance of proposed controller. The chaotic system of a Duffing-Holmes oscillator and an industrial robotic manipulator are the case studies to evaluate the performance of the proposed control approach. The obtained results of this study regarding both systems are compared with the outcomes of two notable studies in the literature. The results and analysis prove the efficiency of the proposed controller with regard to MIMO uncertain systems having challenging external disturbances in terms of stability, minimum tracking error and optimal control inputs.     

嵌入式电子节能控制器的设计与实现

节能控制能够有效降低能耗,对保护环境等方面具有重要影响;但目前大多数电子节能控制器都是通过采用单片机技术和双向晶闸管过零触发交流调压电路对电子节能控制器进行设计;通过介绍电子的负荷特点和节能原理,分析电子节能控制器的硬件组成电路,并对电子节能控制器的主要软件程序的流程图进行设计,完成电子节能控制器设计;但这种方法节能控制效果较低,难以保证电子节能控制器性能,为此,提出一种基于模糊PID控制的嵌入式电子节能控制器设计与实现方法;首先通过对嵌入式电子节能控制器的处理器、电源电路、复位电路、系统时钟电路、JTAG接口电路、D/A转换电路、功放电路、双极性电源电路以及嵌入式电子节能控制器硬件PCB板器件布局等的设计,完成嵌入式电子节能控制器硬件设计;在此基础上,选用模糊PID控制方法对嵌入式电子节能控制器进行设计;通过分析模糊PID控制原理,介绍加入自调节因子的模糊PID控制的算法设计,以此确定输入输出隶属度函数,再利用模糊推理和模糊规则,得到电子节能控制器的模糊控制过程,从而完成嵌入式电子节能控制器的设计;实验证明,所提方法能够有效提高嵌入式电子节能控制器的节能控制效果,具有良好的使用价值。     

基于粒子群优化算法的PID控制器参数整定

PID控制器的性能完全依赖于其参数的整定和优化,但参数的整定及在线自适应调整对常规的PID控制器是难以解决的问题。根据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,提出了一种基于粒子群优化算法整定PID控制器参数的设计方法,并定义了一种新的性能指标函数来评价PID控制器的性能。现以二阶的船舶控制装置为研究对象,运用粒子群优化方法对PID控制器参数进行了寻优研究。仿真结果表明,该方法比一般PID参数整定方法具有更好的控制性能指标,有着一定的工程应用价值。     

Design of PID controller with incomplete derivation based on ant system algorithm

A new and intelligent design method for PID controller with incomplete derivation is proposed based on the ant system algorithm (ASA). For a given control system with this kind of PlD controller, a group of optimal PID controller parameters Kp^*, Ti^*, and Td^* can be obtained by taking the overshoot, settling time, and steady-state error of the system‘s unit step response as the penfomunce indexes and by use of our improved ant system algorithm. Kp^*, Ti^*, and Td^* can be used in real-time control. This kind of controller is called the ASA-PID controller with incomplete derivation. To verify the performance of the ASA-PID controller, three different typical transfer functions were tested, and three existing typical tunmg methods of PID controller parameters,including the Ziegler-Nichols method (ZN), the genetic algnrithrn (GA), and the simulated annealing (SA), were adopted for comparison. The simulation results showed that the ASA-PID controller can be used to control different objects and has better performance compared with the ZN-PID and GA-PID controllers, and comparable performance compared with the SA-PID controller.     

基于改进混合遗传算法的二自由度PID控制器设计与应用

针对一般遗传算法存在的不足,提出一种改进的混合遗传算法,并将其应用于二自由度PID控制器参数寻优设计,仿真试验表明,所设计的二自由度PID控制器具有优良的鲁棒特性和抑制外界于扰特性,在仿真转台控制系统设计中获得了良好的控制效果,从而说明了该方法的有效性。     

基于改进Oustaloup滤波器的分数阶PID控制器简化设计

针对分数阶微积分算子的直接和间接近似化方法所表现出来的形式复杂、运算量大的问题,对Oustaloup滤波器的结构进行改进,对常规分数阶PID控制器进行了简化设计,并采用自适应遗传算法对控制器的参数进行整定.选取两种代表性分数阶系统,在模型处于两种典型状态下,对简化型分数阶PID控制器、常规分数阶PID控制器和整数阶PID控制器的控制性能进行仿真实验对比.结果表明,在控制器性能基本相同的情况下,通过该方法设计的简化型分数阶PID控制器性具有结构简单,耗时量小的优点,提高了工程可实现性.     

典型工业过程鲁棒PID控制器的整定

提出一阶迟延过程、积分迟延过程、不稳定迟延过程和二阶迟延过程等典型工业过程的鲁棒PID整定公式.本文从抗干扰性能和鲁棒性能两方面综合考虑,把鲁棒PID控制器的设计问题转化为求解一个带鲁棒性能约束的绝对误差积分指标(IAE)优化问题.鉴于该问题是非凸的,本文采用遗传算法来求解,并通过曲线拟合得到典型工业过程的PID控制器的整定公式.仿真结果表明本文的PID整定公式有效,且控制器具有良好的抗干扰能力和频域鲁棒性.     

Active disturbance rejection control for power plant with a single loop

The cascade proportional‐integral‐derivative (PID) control method is widely used in power plant control field. In this paper, an active disturbance rejection control (ADRC) for a power plant with a single loop is introduced for eliminating the shortcomings of the cascade PID control method. The proposed controller based on the ADRC method consists of a tracking differentiator (TD), an extended state observer (ESO) and a nonlinear combination of errors. In this approach, the processes with higher orders, uncertainties and unmodeled dynamics are viewed as lower‐ordered systems with general disturbances, and the general disturbances are estimated by ESO, and then actively compensated. Besides, only one measured output is needed in the proposed method instead of two or three in the cascade PID control method. Some simulation studies compared with the regular cascade PID control method show the proposed method has better performance beyond the regular cascade PID control method. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

基于衰减频率特性的PID参数优化整定研究

用衰减频率特性法整定PID控制器可使闭环系统获得要求的衰减比,但是求得的整定参数的解是不确定的,因而难以确定最佳整定参数。就此,将基于衰减频率特性的PID控制器整定问题转换成带衰减比约束的控制器参数优化问题,首先用Matlab计算出整定参数的解曲线或解曲面,然后利用Simulink在仿真环境下寻优,获得期望性能下的最佳整定参数。仿真结果表明所提出的整定方法有效,且控制器具有良好的抗干扰能力。     

PID controller frequency-domain tuning for stable, integrating and unstable processes, including dead-time

In the present paper a new tuning procedure is proposed for the ideal PID controller in series with the first-order noise filter. It is based on the recently proposed extension of the Ziegler-Nichols frequency-domain dynamics characterization of a process G_p(s). Measured process characteristics are the ultimate frequency and ultimate gain, the angle of the tangent to the Nyquist curve of the process at the ultimate frequency, and G_p(0). For a large class of processes the same tuning formulae can be effectively applied to obtain closed-loop responses with predictable properties. Load disturbance step responses without the undershoot and reference step responses with negligible overshoot are obtained by analyzing a test batch consisting of stable, integrating and unstable processes, including dead-time and oscillatory dynamics. The proposed tuning makes possible to specify the desired sensitivity to the high frequency measurement noise and the desired maximum sensitivity. Comparison with the optimal ideal PID controller in series with the first-order noise filter is presented and discussed. The extension of the proposed method to the PI controller tuning is direct. Comparison with the optimal PI controller is presented and discussed.     

Interval-model-based global optimization framework for robust stability and performance of PID controllers

PID controller structure is regarded as a standard in the control-engineering community and is supported by a vast range of automation hardware. Therefore, PID controllers are widely used in industrial practice. However, the problem of tuning the controller parameters has to be tackled by the control engineer and this is often not dealt with in an optimal way, resulting in poor control performance and even compromised safety. The paper proposes a framework, which involves using an interval model for describing the uncertain or variable dynamics of the process. The framework employs a particle swarm optimization algorithm for obtaining the best performing PID controller with regard to several possible criteria, but at the same time taking into account the complementary sensitivity function constraints, which ensure robustness within the bounds of the uncertain parameters’ intervals. Hence, the presented approach enables a simple, computationally tractable and efficient constrained optimization solution for tuning the parameters of the controller, while considering the eventual gain, pole, zero and time-delay uncertainties defined using an interval model of the controlled process. The results provide good control performance while assuring stability within the prescribed uncertainty constraints. Furthermore, the controller performance is adequate only if the relative system perturbations are considered, as proposed in the paper. The proposed approach has been tested on various examples. The results suggest that it is a useful framework for obtaining adequate controller parameters, which ensure robust stability and favorable control performance of the closed-loop, even when considerable process uncertainties are expected.     

An alternative structure for next generation regulatory controllers: Part I: Basic theory for design, development and implementation

Even though employed widely in industrial practice, the popular PID controller has weaknesses that limit its achievable performance, and an intrinsic structure that makes tuning not only more complex than necessary, but also less transparent with respect to the key attributes of the overall controller performance, namely: robustness, set-point tracking, and disturbance rejection. In this paper, we propose an alternative control scheme that combines the simplicity of the PID controller with the versatility of model predictive control (MPC) while avoiding the tuning problems associated with both. The tuning parameters of the proposed control scheme are related directly to the controller performance attributes; they are normalized to lie between 0 and 1; and they arise naturally from the formulation in a manner that makes it possible to tune the controller directly for each performance attribute independently. The result is a controller that can be designed and implemented much more directly and transparently, and one that outperforms the classical PID controller both in set-point tracking and disturbance rejection while using precisely the same process reaction curve information required to tune PID controllers. The design, implementation and performance of the controller are demonstrated via simulation on a nonlinear polymerization process.     

基于Pade近似一般形式的IMC-PID控制器设计

内模控制方法因具有诸多优点而引起了业界的广泛关注,但难以在DCS中直接实现,现有的IMC-PID设计方法存在着只针对特定模型才能设计或通用设计但近似程度偏低的问题,提出了一种新的IMC-PID控制器设计方法,采用一般形式的Pade多项式逼近IMC-PID转化过程中出现的复杂项,然后对照该Pade多项式和PID控制器表达式设计PID控制器参数.该方法广泛适用于各种单变量对象,也能够毫无修改地应用于多变量系统的IMC-PID控制器参数设计.与基于Maclaurin展式的IMC-PID设计方法相比,该方法提供了具有更强理论依据的微分滤波时间常数计算式,能够获得与内模策略更为接近的控制效果.     

Backstepping approach for design of PID controller with guaranteed performance for micro-air UAV

Flight controllers for micro-air UAVs are generally designed using proportional-integral-derivative (PID) methods, where the tuning of gains is difficult and time-consuming, and performance is not guaranteed. In this paper, we develop a rigorous method based on the sliding mode analysis and nonlinear backstepping to design a PID controller with guaranteed performance. This technique provides the structure and gains for the PID controller, such that a robust and fast response of the UAV (unmanned aerial vehicle) for trajectory tracking is achieved. First, the second-order sliding variable errors are used in a rigorous nonlinear backstepping design to obtain guaranteed performance for the nonlinear UAV dynamics. Then, using a small angle approximation and rigorous geometric manipulations, this nonlinear design is converted into a PID controller whose structure is naturally determined through the backstepping procedure. PID gains that guarantee robust UAV performance are finally computed from the sliding mode gains and from stabilizing gains for tracking error dynamics. We prove that the desired Euler angles of the inner attitude controller loop are related to the dynamics of the outer backstepping tracker loop by inverse kinematics, which provides a seamless connection with existing built-in UAV attitude controllers. We implement the proposed method on actual UAV, and experimental flight tests prove the validity of these algorithms. It is seen that our PID design procedure yields tighter UAV performance than an existing popular PID control technique.     

基于两自由度PID-准谐振控制器的永磁同步电机转矩脉动抑制方法

由于功率变换器死区、磁链谐波等非线性因素的存在,导致电机相电流中含有大量高次谐波,因而电流与磁链共同作用后产生的电磁转矩中也含有各种阶次的谐波,这使得转矩呈现出一种周期性的波动特性,称为转矩脉动。为解决这一问题,分析了转矩脉动产生的原因,为消除引起转矩脉动的谐波电流提出一种PI控制器与准谐振控制器相并联的控制结构。然而,谐振控制器的加入导致电流环响应超调的增加,因此引入两自由度PID控制器以减小电流超调,最终得到一种两自由度PID并联准谐振控制器的控制结构。最后,通过仿真实验对各种控制结构的对比研究,验证了所提方法的有效性。     

四旋翼飞行器的自抗扰飞行控制方法

针对四旋翼飞行器参数不确定性和外部干扰敏感的问题,本文提出一种基于自抗扰控制器的控制系统设计方法.在为期望姿态和高度安排过渡过程的基础上,设计了扩张状态观测器对内扰和外扰进行估计并实时补偿,能够很好地克服飞行器的强耦合性、模型不确定性以及风速变化等外部干扰问题.此外本文还设计了非线性状态误差反馈控制律来有效抑制跟踪误差.在仿真平台上对自抗扰控制系统进行稳定控制、姿态跟踪、高度控制、抗扰性及鲁棒性实验,并与串级PID控制系统进行定量对比分析.仿真结果表明,本文所设计的自抗扰控制器不仅能够很好地估计并补偿系统所受内外部干扰,而且对四旋翼飞行器参数的不确定性具有较强的鲁棒性,能够满足飞行器姿态调节快速和高稳定度的控制要求,性能指标明显优于串级PID控制器.