Constrained self-adaptive differential evolution based design of robust optimal fixed structure controller

This paper presents a constrained Self-adaptive Differential Evolution (SaDE) algorithm for the design of robust optimal fixed structure controllers with uncertainties and disturbance. Almost all real world optimization problems have constraints which should be satisfied along with the best optimal solution for the problem. In evolutionary algorithms (EAs) the presence of constraints reduces the feasible region and complicates the search process. Therefore, a suitable method to handle the constraints must also be executed. In the SaDE algorithm, four mutation strategies and the control parameter CR are self-adapted. Self-adaptive Penalty (SP) method is introduced into the SaDE algorithm for constraint handling. The performance of SaDE algorithm is demonstrated on the design of robust optimal fixed structure controller of three systems, namely the linearized magnetic levitation system, F-8 aircraft linearized model and a SISO plant. For the comparison purpose, reported results of constrained PSO algorithm and five DE algorithms with different strategies and parameter values are taken into account. Statistical performance in 20 independent runs is considered to compare the performance of algorithms. From the obtained results, it is observed that SaDE algorithm is able to self-adapt the mutation strategy and the crossover rate and hence performs better than the other variants of DE and the constrained PSO algorithm. Better performance of SaDE is achieved by sustained maintenance of diversity throughout the evolutionary process thus producing better individuals consistently. This also aids the algorithm to escape from local optima thereby avoiding premature convergence.     

差分进化算法参数控制与适应策略综述

差分进化算法逐渐成为进化计算领域最流行的随机搜索算法之一,已被成功用于求解各类应用问题.差分进化算法参数设置与其性能密切相关,因此算法参数控制与适应策略设计是目前该领域的研究热点之一,目前已涌现出大量参数控制方案,但尚缺乏系统性的综述与分析.首先简要介绍差分进化算法的基本原理与操作,然后将目前参数控制与适应策略分成基于经验的参数控制、参数随机化适应策略、基于统计学习的参数随机化适应策略和参数自适应策略4类进行系统性综述,重点介绍其中的参数适应与自适应策略.此外,为分析各种参数控制与适应策略的功效,以实值函数优化为问题背景设计了相关实验,进一步分析各种策略的效率与实用性,实验结果表明,参数自适应控制策略是目前该领域最有效的方法之一.     

进化设计中拓扑搜索和参数的协同优化算法

为了解决基于遗传编程(GP)的动态系统进化设计过程中拓扑和参数协同优化的问题,讨论了基于GP的进化设计种群拓扑多样性保存策略,提出了一种拓扑适应值共享-拥挤协同搜索算法。该算法避免计算小生境半径、通过自适应适应度函数来惩罚拓扑子群,保证了拓扑多样性和阻止局部收敛的发生。实验结果表明,该算法保证了动态系统进化设计中拓扑和参数同步搜索的平衡,有效地克服了局部收敛,能确保获得理想的设计结果。     

A novel adaptive control strategy for decomposition-based multiobjective algorithm

Recently, evolutionary algorithm based on decomposition (MOEA/D) has been found to be very effective and efficient for solving complicated multiobjective optimization problems (MOPs). However, the selected differential evolution (DE) strategies and their parameter settings impact a lot on the performance of MOEA/D when tackling various kinds of MOPs. Therefore, in this paper, a novel adaptive control strategy is designed for a recently proposed MOEA/D with stable matching model, in which multiple DE strategies coupled with the parameter settings are adaptively conducted at different evolutionary stages and thus their advantages can be combined to further enhance the performance. By exploiting the historically successful experience, an execution probability is learned for each DE strategy to perform adaptive adjustment on the candidate solutions. The proposed adaptive strategies on operator selection and parameter settings are aimed at improving both of the convergence speed and population diversity, which are validated by our numerous experiments. When compared with several variants of MOEA/D such as MOEA/D, MOEA/D-DE, MOEA/D-DE+PSO, ENS-MOEA/D, MOEA/D-FRRMAB and MOEA/D-STM, our algorithm performs better on most of test problems.     

时变大滞后系统的模糊免疫PID控制

工业中的大多数生产系统都是时变和滞后系统。对于这类系统,普通的PID控制器难以获得满意的控制效果。而采用模糊PID控制能降低系统的超调量,提高系统的响应速度。为了提高模糊PID控制器的控制性能,将模糊参数自整定调节方法与免疫进化算法相结合,设计了一种模糊免疫参数自整定PID控制系统。对于时变大滞后系统,模糊免疫参数自整定PID控制能明显减小系统的超调量,加快系统的响应速度。     

Self-Adapting Control Parameters in Differential Evolution: A Comparative Study on Numerical Benchmark Problems

We describe an efficient technique for adapting control parameter settings associated with differential evolution (DE). The DE algorithm has been used in many practical cases and has demonstrated good convergence properties. It has only a few control parameters, which are kept fixed throughout the entire evolutionary process. However, it is not an easy task to properly set control parameters in DE. We present an algorithm-a new version of the DE algorithm-for obtaining self-adaptive control parameter settings that show good performance on numerical benchmark problems. The results show that our algorithm with self-adaptive control parameter settings is better than, or at least comparable to, the standard DE algorithm and evolutionary algorithms from literature when considering the quality of the solutions obtained     

基于元胞多目标遗传算法的蜗杆优化设计

为研究蜗杆传动的多目标优化问题,提出一种自适应差分进化的元胞多目标遗传算法。该算法针对元胞遗传算法的特点,对基本的差分进化策略进行改进,得到一种参数自适应控制策略。将该算法与目前性能优异的4种多目标进化算法在三目标的基准测试函数进行对比实验,结果表明所提算法相对于其他算法具有明显的优势,能够在保证良好收敛性的同时,使获得的Pareto前端分布性更加均匀,覆盖范围更广;工程实例求解结果也表明了算法的工程可行性。     

Hybrid evolutionary algorithm for microscrew thread parameter estimation

In this paper we propose a novel approach to the problem of microscrew thread parameter estimation based on a hybrid evolutionary algorithm that combines a stochastic evolutionary algorithm with the deterministic inverse parabolic interpolation. The proposed method uses a machine vision system utilizing a single web camera. The hybrid evolutionary algorithm was tested on a specially created image database of microscrews. Experimental results prove speed and efficiency of the proposed method and its robustness to noise in the images. This method may be used in automated systems of real-time non-destructive quality control of microscrews and has potential for parameter estimation of different types of microparts.     

一种求解多目标优化问题的进化算法混合框架

为了提高多目标优化算法的求解性能,提出一种启发式的基于种群的全局搜索与局部搜索相结合的多目标进化算法混合框架.该框架采用模块化、系统化的设计思想,不同模块可以采用不同策略构成不同的算法.采用经典的改进非支配排序遗传算法(NSGA-II)和基于分解的多目标进化算法(MOEA/D)作为进化算法的模块算法来验证所提混合框架的有效性.数值实验表明,所提混合框架具有良好性能,可以兼顾算法求解的多样性和收敛性,有效提升现有多目标进化算法的求解性能.     

A novel improved particle swarm optimization algorithm based on individual difference evolution

As a well-known stochastic optimization algorithm, the particle swarm optimization (PSO) algorithm has attracted the attention of many researchers all over the world, which has resulted in many variants of the basic algorithm, in addition to a vast number of parameter selection/control strategies. However, most of these algorithms evolve their population using a single fixed pattern, thereby reducing the intelligence of the entire swarm. Some PSO-variants adopt a multimode evolutionary strategy, but lack dynamic adaptability. Furthermore, competition among particles is ignored, with no consideration of individual thinking or decision-making ability. This paper introduces an evolution mechanism based on individual difference, and proposes a novel improved PSO algorithm based on individual difference evolution (IDE-PSO). This algorithm allocates a competition coefficient called the emotional status to each particle for quantifying individual differences, separates the entire swarm into three subgroups, and selects the specific evolutionary method for each particle according to its emotional status and current fitness. The value of the coefficient is adjusted dynamically according to the evolutionary performance of each particle. A modified restarting strategy is employed to regenerate corresponding particles and enhance the diversity of the population. For a series of benchmark functions, simulation results show the effectiveness of the proposed IDE-PSO, which outperforms many state-of-the-art evolutionary algorithms in terms of convergence, robustness, and scalability.     

Parameter Control of Genetic Algorithms by Learning and Simulation of Bayesian Networks — A Case Study for the Optimal Ordering of Tables

Parameter setting for evolutionary algorithms is still an important issue in evolutionary computation. There are two main approaches to parameter setting: parameter tuning and parameter control. In this paper, we introduce self-adaptive parameter control of a genetic algorithm based on Bayesian network learning and simulation. The nodes of this Bayesian network are genetic algorithm parameters to be controlled. Its structure captures probabilistic conditional (in)dependence relationships between the parameters. They are learned from the best individuals, i.e., the best configurations of the genetic algorithm. Individuals are evaluated by running the genetic algorithm for the respective parameter configuration. Since all these runs are time-consuming tasks, each genetic algorithm uses a small-sized population and is stopped before convergence. In this way promising individuals should not be lost. Experiments with an optimal search problem for simultaneous row and column orderings yield the same optima as state-of-the-art methods but with a sharp reduction in computational time. Moreover, our approach can cope with as yet unsolved high-dimensional problems.     

Parameter control in evolutionary algorithms

The issue of controlling values of various parameters of an evolutionary algorithm is one of the most important and promising areas of research in evolutionary computation: it has a potential of adjusting the algorithm to the problem while solving the problem. In the paper we: 1) revise the terminology, which is unclear and confusing, thereby providing a classification of such control mechanisms, and 2) survey various forms of control which have been studied by the evolutionary computation community in recent years. Our classification covers the major forms of parameter control in evolutionary computation and suggests some directions for further research     

Using genetic algorithms to establish efficient walking gaits for an eight-legged robot

In the design and development of a legged robot, many factors need to be considered. As a consequence, creating a legged robot that can efficiently and autonomously negotiate a wide range of terrains is a challenging task. Many researchers working in the area of legged robotics have traditionally looked towards the natural world for inspiration and solutions, reasoning that these evolutionary solutions are appropriate and effective because they have passed the hard tests for survival over time and generations. This paper reports the use of genetically inspired learning strategies, commonly referred to as genetic algorithms, as an evolutionary design tool for improving the design and performance of an algorithm for controlling the leg stepping sequences of a walking robot. The paper presents a specific case of finding optimal walking gaits for an eightlegged robot called Robug IV and simulated results are provided.     

基于均匀设计的差分进化算法的参数设定

差分进化算法参数的设定多采用经验选取方式,其缺点是试验运行量大以及难以得到最优参数组合,从而在很大程度上影响了算法的寻优能力。将均匀设计的试验方法引入差分进化算法的参数设定中,通过对单峰函数、多峰函数和病态函数等3种不同类型的标准测试函数进行均匀设计试验,找出适合不同类型标准测试函数的最优参数组合,从而达到对差分进化算法的参数进行设定的目的。结果显示,将经过均匀设计试验得到的两组最优的参数组合用于差分进化算法时,所获得的平均全局最优解为4.3215,平均标准差为3.650。可见,利用均匀试验设计方法对基本差分进化算法的参数进行设定是可行且有效的,同时具有较好的稳定性。     

Robust Evolutionary Algorithm Design for Socio-economic Simulation

Agent-based computational economics (ACE) combines elements from economics and computer science. In this paper, we focus on the relation between the evolutionary technique that is used and the economic problem that is modeled. In the field of ACE, economic simulations often derive parameter settings for the evolutionary algorithm directly from the values of the economic model parameters. In this paper, we compare two important approaches that are dominating ACE research and show that the above practice may hinder the performance of the evolutionary algorithm and thereby hinder agent learning. More specifically, we show that economic model parameters and evolutionary algorithm parameters should be treated separately by comparing the two widely used approaches to social learning with respect to their convergence properties and robustness. This leads to new considerations for the methodological aspects of evolutionary algorithm design within the field of ACE.     

Self-Adaptive Evolutionary Extreme Learning Machine

In this paper, we propose an improved learning algorithm named self-adaptive evolutionary extreme learning machine (SaE-ELM) for single hidden layer feedforward networks (SLFNs). In SaE-ELM, the network hidden node parameters are optimized by the self-adaptive differential evolution algorithm, whose trial vector generation strategies and their associated control parameters are self-adapted in a strategy pool by learning from their previous experiences in generating promising solutions, and the network output weights are calculated using the Moore?CPenrose generalized inverse. SaE-ELM outperforms the evolutionary extreme learning machine (E-ELM) and the different evolutionary Levenberg?CMarquardt method in general as it could self-adaptively determine the suitable control parameters and generation strategies involved in DE. Simulations have shown that SaE-ELM not only performs better than E-ELM with several manually choosing generation strategies and control parameters but also obtains better generalization performances than several related methods.     

基于IGA的支持向量机特征子集选择和参数优化

特征子集选择和训练参数的优化一直是SVM研究中的两个重要方面,选择合适的特征和合理的训练参数可以提高SVM分类器的性能,以往的研究是将两个问题分别进行解决。随着遗传优化等自然计算技术在人工智能领域的应用,开始出现特征选择及参数的同时优化研究。研究采用免疫遗传算法（IGA）对特征选择及SVM 参数的同时优化,提出了一种IGA-SVM 算法。实验表明,该方法可找出合适的特征子集及SVM 参数,并取得较好的分类效果,证明算法的有效性。     

Robust design of multilayer optical coatings by means ofevolutionary algorithms

Robustness is an important requirement for almost all kinds of products. This article shows how evolutionary algorithms can be applied for robust design based on the approach of Taguchi. To achieve a better understanding of the consequences of this approach, we first present some analytical results gained from a toy problem. As a nontrivial industrial application we consider the design of multilayer optical coatings (MOCs) most frequently used for optical filters. An evolutionary algorithm based on a parallel diffusion model and extended for mixed-integer optimization was able to compete with or even outperform traditional methods of robust MOC design. With respect to chromaticity, the MOC designs found by the evolutionary algorithm are substantially more robust to parameter variations than a reference design and therefore perform much better in the average case. In most cases, however, this advantage has to be paid for by a reduction in the average reflectance. The robust design approach outlined in this paper should be easily adopted to other application domains     

演化算法的最优轨道分析

基于最优控制理论,提出了演化算法的一种最优轨道分析方法.将演化算法描述成一个动力系统,定义了它的时间最优控制模型.运用著名的Pontryagain极大值原理,分析了演化算法的最优轨道,并利用矩阵范数理论对最优轨道进行了一些理论估计.同时将理论分析结果应用于演化算法的设计之中,导出了一种新的选择策略和终止条件.     

An optimality criteria based method for discrete design optimization taking into account buildability constraints

This paper presents a heuristic design optimization method specifically developed for practicing structural engineers. Practical design optimization problems are often governed by buildability constraints. The majority of optimization methods that have recently been proposed for design optimization under buildability constraints are based on evolutionary computing. While these methods are generally easy to implement, they require a large number of function evaluations (finite element analyses), and they involve algorithmic parameters that require careful tuning. As a consequence, both the computation time and the engineering time are high. The discrete design optimization algorithm presented in this paper is based on the optimality criteria method for continuous optimization. It is faster than an evolutionary algorithm and it is free of tuning parameters. The algorithm is successfully applied to two classical benchmark problems (the design of a ten-bar truss and an eight-story frame) and to a practical truss design optimization problem.