A nonlinear PID-based multiple controller incorporating a multilayered neural network learning submodel

A new nonlinear minimum-variance adaptive proportional integral derivative (PID) based multiple controller, incorporating a multi- layered neural network learning submodel, is presented. The unknown non-linear plant is represented by an equivalent stochastic model consisting of a linear least-squares-based submodel plus a non- linear multi-layered back propagation (BP) neural network-based learning submodel. The proposed multiple controller methodology provides the designer with a choice of using either a conventional PID self-tuning controller, a PID structure-based pole-placement controller, or a newly proposed PID structure-based pole-zero placement controller through simple switching. The novel PID structure based pole-zero placement controller employs an adaptive mechanism, which ensures that the closed-loop poles and zeros are located at their prespecified positions. The switching decision between the different nonlinear fixed structure controllers is made manually in the present case but can be automated using fuzzy logic or stochastic learning automata techniques. Simulation results using a nonlinear plant model demonstrate the effectiveness of the proposed multiple controller with respect to tracking set-point changes. The aim is to achieve a desired speed of response while penalizing excessive control action, for applications in nonminimum phase and unstable systems

Nonlinear predictive control of flexible manipulator systems

This paper looks at nonlinear predictive control of flexible manipulator system

Optimized discrete-time state dependent Riccati equation regulator

The state dependent Riccati equation was originally developed for the continuous time systems. In the paper the optimality of a discrete time version of the state dependent Riccati equation is considered. The derivation of the optimal control strategy is based on the Hamiltonian optimal solution for the nonlinear optimal control problem. The new form of the discrete state dependent Riccati equation with a correction tensor is derived. The prediction of the future trajectory is used in the derivation

Editorial: Nonlinear adaptive PID control - Part II

The article provides an overview of papers about nonlinear adaptive proportional integral derivative (PID) control, published in the August 2006 issue of "Control and Intelligent Systems." Zayed and colleagues wrote an editorial describing a nonlinear adaptive PID-based multiple controller methodology. Skoczowski and colleagues focused on the properties of model-following control systems. Nezli and colleagues presented a new control design procedure for permanent magnet synchronous motor

Editorial: Nonlinear adaptive PID control - Part II

The article provides an overview of papers about nonlinear adaptive proportional integral derivative (PID) control, published in the August 2006 issue of "Control and Intelligent Systems." Zayed and colleagues wrote an editorial describing a nonlinear adaptive PID-based multiple controller methodology. Skoczowski and colleagues focused on the properties of model-following control systems. Nezli and colleagues presented a new control design procedure for permanent magnet synchronous motor

Synthesis of isomaltooligosaccharides and oligodextrans by the combined use of dextransucrase and dextranase

Batch syntheses of isomaltooligosaccharides (IMO) from sucrose, using the enzymes dextransucrase and dextranase were performed with the aim of understanding the reaction mechanism and the parameters which affect product characteristics and molecular size. Both activities described for dextransucrase (dextran formation and acceptor reaction) achieved synthesis whilst the hydrolytic activity of dextranase regulated the product molecular size and acceptor availability. Depending on the reaction conditions, the product oligosaccharide mixtures contained mainly sugars (up to 36%) with degrees of polymerization (DP) varying between 10 and 60 together with lower concentrations of both lower and higher molecular weight sugars. Alterations in substrate and dextranase concentrations (50-400 mg ml(-1) and 2.5-46 U ml(-1), respectively) affected the molecular weight of IMO, the reaction rate and the formation of leucrose. This permitted manipulation of the product characteristics. It was found that higher substrate and dextranase concentrations gave rise to products with lower molecular sizes and a dextransucrase:dextranase ratio of 1: 1 or 1:2 appeared to produce a polymer with a molecular weight which is desirable for prebiotic use. (C) 2004 Elsevier Inc. All rights reserved