Simple fractional order controller combined with a Smith predictor for temperature control in a steel slab reheating furnace

This paper proposes a simple fractional order controller combined with a Smith predictor scheme for controlling the temperature of a steel slab reheating furnace. The dynamic model of the preheating zone of this process is obtained from an identification procedure applied in an industrial furnace. This identification procedure yields a second order plus time delay transfer function which undergoes large time delay changes. A fractional order integral controller combined with a Smith predictor is therefore designed. Simulated results compare the performances of the proposed fractional order controller with a standard PI controller, also combined with a Smith predictor, an LQR controller, and an H _∞ robust controller, in the case of the nominal process, and when the time delay varies. Four performance indexes have been used in this comparison: three related to the output performance (settling time, overshooting, and integral absolute error (IAE)), and a fourth one related to the control effort (TV). The analysis of these indexes shows that the simple fractional order controller provides lower values of the compared indexes when time delay becomes much higher than the nominal value.     

ADALINE based robust control in robotics: a Riemann-Liouville fractional differintegration based learning scheme

This paper presents an approach to improve the performance of intelligent sliding model control achieved by the use of a fundamental constituent of soft computing, named Adaptive Linear Element (ADALINE). The proposed scheme is based on the fractional calculus. A previously considered tuning scheme is revised according to the rules of fractional order differintegration. After a comparison with the integer order counterpart, it is seen that the control system with the proposed adaptation scheme provides (1) better tracking performance, (2) suppression of undesired drifts in parameter evolution and (3) a very high degree of robustness and insensitivity to disturbances. The claims are justified through some simulations utilizing the dynamic model of a two degrees of freedom (DOF) direct drive robot arm and overall, the contribution of the paper is to introduce the fractional order calculus into a robust and nonlinear control problem with some outperforming features that are absent when the integer order differintegration operators are adopted.     

A self-tuning Smith predictor applied to the control of blood pressure: simulation studies

Significant time-delays occur in the response of blood pressure to drug therapy. The classical Smith predictor algorithm used to eliminate such delays is extended here to the principle of self-tuning under mis-match conditions. Two delay-free controller algorithms are investigated, being a self-tuning pole-placement and a self-tuning PID structure. Extensive simulation studies using the well-known Slate model have demonstrated the good transient performance obtained with this self-tuning Smith principle in various combinations, and under realistic variability of patient dynamics.     

Fuzzy-PID复合控制在温室节水灌溉中的应用

为解决温室节水灌溉的需求,综合考虑温室环境因子对灌溉量的影响,通过系统辨识的方法,建立被控对象土壤湿度的数学模型.针对湿度控制大滞后惯性环节的特点,设计了一种Fuzzy-PID复合控制的方法.该方法将模糊控制器和PID控制器并行结合,并采用梯形隶属函数的模糊切换算法进行两者的切换,实现两种控制方法的优势互补.实验仿真结果表明:Fuzzy-PID复合控制响应时间短、超调量小、稳态过程没有振荡,不仅具有较好的动态性能,而且具有比较理想的稳态品质,适用于温室节水灌溉控制.     

Neural network-based Smith predictor design for the time-delay in a tele-operated control system

This article presents a methodology for compensating for the time-delay effects in tele-operated control systems. Compensation can be carried out by a neural network. A tele-operated system consists of a master robot to give commands, and a slave robot to work with the environment. The positional command by the master robot is transferred to the slave robot, and the contact force from the environment is transferred back to the master robot. The structure of the Smith predictor is modified by replacing the linear estimator with a neural network whose structure is based on the radial basis function (RBF). The RBF network identifies the slave model to deal with the nonlinearities in the system. Simulation studies have been conducted, and experimental studies of one-directional force control were performed to confirm the simulation results.     

Application of robust control techniques to a mobile robot system

This article deals with the stabilization problem of a class of nonlinear second-order multivariable dynamical systems with bounded uncertainties. A robust discontinuous controller is proposed to guarantee asymptotic stability of this class of systems. Then, to guarantee the continuity of the control, a quasi-saturation function is introduced into the control law. Guaranteed eventual stability-in-the-large (ESL) of the dynamical systems is proved with the continuous, robust controller, which is much different from the standard “computed-torque control.” The controller requires known bounding functions that are easier to determine as well as more general than the bounds needed in other approaches. An application is given to trajectory-following control for a two-link mobile robot. © 1992 John Wiley & Sons Inc.     

基于GPRS网的节水灌溉远程控制系统研究

提出了一种基于GPRS网的节水灌溉远程控制系统.利用Winsock网络编程技术和GPRS网的资源实现了数据远程无线传输与现场控制;采用ADO数据库访问技术和SQL数据库实现了数据管理与处理.现场计算机控制软件采用模糊控制理论,可实现无人化灌溉管理作业;重点研究了客户机、中心服务器和下位机之间的数据通信流程、通信帧协议及软件设计.该系统为科学实现农田节水提供了一条途径.     

Application of fractional order theory of magneto-thermoelasticity to an infinite perfect conducting body with a cylindrical cavity

A fractional model of the equations of generalized magneto-thermoelasticity for a perfect conducting isotropic thermoelastic media is given. This model is applied to solve a problem of an infinite body with a cylindrical cavity in the presence of an axial uniform magnetic field. The boundary of the cavity is subjected to a combination of thermal and mechanical shock acting for a finite period of time. The solution is obtained by a direct approach by using the thermoelastic potential function. Laplace transform techniques are used to derive the solution in the Laplace transform domain. The inversion process is carried out using a numerical method based on Fourier series expansions. Numerical computations for the temperature, the displacement and the stress distributions as well as for the induced magnetic and electric fields are carried out and represented graphically. Comparisons are made with the results predicted by the generalizations, Lord–Shulman theory, and Green–Lindsay theory as well as to the coupled theory.

     

The multistage homotopy analysis method: application to a biochemical reaction model of fractional order

In this paper, a new reliable algorithm called the multistage homotopy analysis method (MHAM) based on an adaptation of the standard homotopy analysis method (HAM) is presented to solve a time-fractional enzyme kinetics. This enzyme–substrate reaction is formed by a system of nonlinear ordinary differential equations of fractional order. The new algorithm is only a simple modification of the HAM, in which it is treated as an algorithm in a sequence of small intervals (i.e. time step) for finding accurate approximate solutions to the corresponding systems. Numerical comparisons between the MHAM and the classical fourth-order Runge–Kutta method in the case of integer-order derivatives reveal that the new technique is a promising tool for nonlinear systems of integer and fractional order.     

Genetic algorithm based approaches to solve the order batching problem and a case study in a distribution center

Journal of Intelligent Manufacturing - The order batching problem is a combinatorial optimization problem that arises in the warehouse order picking process. In the order batching problem, the aim...     

Water balance study and conjunctive water use planning in an irrigation canal command area: A remote sensing perspective

Water budgeting of the D-36 and D-36 A distributaries confined between Pedda Vagu, Korutla Vagu and Kakatiya main canal of the Sri RamSagar Project (SRSP) Command area was conducted using remote sensing derived crop areas, land cover information, irrigation tank inventory and source-wise distribution of irrigated areas, together with conventional meteorological, canal flows and well inventory data. A semi-empirical water balance model was developed and validated using remote sensing derived objective information of the command area and the validated model used for predicting the groundwater table under normal rainfall conditions. Recharge and water balance in the study area indicated that the net recharge to the aquifer is negative to the tune of 2.54 Mm³ resulting in a fall of the groundwater table by 0.79 m during 1992-93. However, normalized groundwater recharge and water balance estimates indicate an impending waterlogging problem with an annual groundwater table rise of 0.35 m. In view of existing water management practices, a conjunctive water use plan of rotational operation of aquifers and canals is suggested.     

Experimental results applying second order sliding mode control to a PEM fuel cell based system

A robust control solution is proposed to solve the air supply control problem in autonomous polymer electrolyte membrane fuel cells (PEMFC) based systems. A Super Twisting controller is designed using a nonlinear model of a laboratory fuel cell test station, even a Lyapunov based stability discussion is included. Subsequently, the proposed control strategy is successfully implemented in the laboratory test bench. Highly satisfactory results are obtained, regarding dynamic behaviour, oxygen stoichiometry regulation and robustness against uncertainty.     

Fractional order robust control for cogging effect compensation in PMSM position servo systems: Stability analysis and experiments

Fractional calculus is a generalization of the integration and differentiation to the fractional (non-integer) order. In this paper, for the first time, a fractional order robust control (FO-RC) method is devised for cogging effect compensation on permanent magnetic synchronous motors (PMSM) position and velocity servo system. In this FO-RC scheme, a fractional order robust controller is designed to compensate the cogging effect, and guarantee the boundedness of all signals. Stability properties have been proven for the systems with the traditional integer order robust control method and the proposed fractional order robust control scheme, respectively. Simulation illustration and experimental validation are presented to show the advantage of the proposed FO-RC scheme for cogging effect compensation over the conventional integer order method.     

PLC控制系统在港口煤场洒水除尘工程中的应用

本文完成了秦皇岛港口煤炭作业洒水除尘工程中PLC控制系统的理论研究、方案设计及工程实现,着重介绍了对洒水喷枪、变频器和喷枪启动顺序的控制。     

Improvement of robust digital control by identification in the closed loop. Application to a 360° flexible arm

This paper presents a procedure for the improvement of identification results from open-loop experiments by identification in a closed loop without modification of the identification protocol. Several available identification algorithms are considered, and two methods for the validation of the model identified in a closed loop are introduced. As a consequence, an improved robust controller is obtained. Results are presented from experiments on a very flexible 360° arm.     

Particle swarm optimization based tuning of a modified smith predictor for mould level control in continuous casting

Mould level variations are a serious productivity and quality problem in continuous casting process. This work proposes a level control structure based on the Aström's modified Smith predictor able to improve the bulging effect rejection. Unlike conventional methods, this control strategy decouples the disturbance rejection from the setpoint response and therefore can be independently optimized. Using this scheme, the bulging rejection specifications are reformulated as a H_∞ problem and the tuning parameters are designed through the particle swarm optimization approach. Simulation results confirm that the proposed architecture is more effective than the other ones currently implemented in real plants.     

Application of partial mutual information variable selection to ANN forecasting of water quality in water distribution systems

Recent trends in the management of water supply have increased the need for modelling techniques that can provide reliable, efficient, and accurate representation of the complex, non-linear dynamics of water quality within water distribution systems. Statistical models based on artificial neural networks (ANNs) have been found to be highly suited to this application, and offer distinct advantages over more conventional modelling techniques. However, many practitioners utilise somewhat heuristic or ad hoc methods for input variable selection (IVS) during ANN development.This paper describes the application of a newly proposed non-linear IVS algorithm to the development of ANN models to forecast water quality within two water distribution systems. The intention is to reduce the need for arbitrary judgement and extensive trial-and-error during model development. The algorithm utilises the concept of partial mutual information (PMI) to select inputs based on the analysis of relationship strength between inputs and outputs, and between redundant inputs. In comparison with an existing approach, the ANN models developed using the IVS algorithm are found to provide optimal prediction with significantly greater parsimony. Furthermore, the results obtained from the IVS procedure are useful for developing additional insight into the important relationships that exist between water distribution system variables.     

单片机在软化水设备自动控制系统中的应用

本文设计了一种用于软化水设备的自动控制系统,系统采用单片机和多功能外围部件组成。文章详细介绍了系统的工作原理,并对系统的整体结构、硬件配置、软件功能分别作了说明。实际运行表明,该系统电路简单,运行稳定,系统可靠性高。     

Application of a fractional step method for the numerical solution of the shallow water waves in a rotating rectangular basin

A numerical method is applied to the problem of an incompressible fluid in a slowly rotating rectangular basin for the simulation of wave propagation in shallow water. The present work is a complete study of the wave motion through evaluation of the wave height and the velocity components. The results are found by the application of a fractional step method and illustrated graphically. The technique is applied by splitting the shallow water equations and successive integration in every direction along the characteristics using the Riemann invariants associated with cubic spline interpolation. It has the advantage of reducing the multidimensional matrix inversion problem into an equivalent one-dimensional problem. Numerical results are represented in three dimensions for the velocity components at different times. The distribution of temperature and concentration are also calculated and plotted.