Tetsuzo Sakamoto

Modelling and analysis of a web tension control system

The paper describes the mathematical treatments and simulations for an experimental web tension control system. Differential equations for the web dynamics are formulated systematically for the system including a dancer roll to construct the block diagram. The web itself could be expressed in terms of fundamental elements, but it is concluded that the elastic or Maxwell models may not be proper ways to describe it. Simulations are performed on the model which has PI controllers, to clarify the physical phenomena and to see the validity of the mathematical model.

Propulsion control of superconducting linear synchronous motor vehicle

The armature current of a superconducting Linear Synchronous Motor (LSM) for a maglev vehicle is controlled to produce a suitable propulsion force so that the vehicle follows the reference speed signal sent from a control station. Besides the power is supplied from some inverters to the LSM armature sections where the vehicle exists. This paper shows an exact mathematical modeling of the propulsion control system to treat the system analytically, which is used for designing controllers and performance computer simulations. The calculated results include the simulations when the vehicle goes through power feeder section borders and tunnels that have a large aerodynamic drag force with account taken of inverter failure.

Decentralized control strategies for web tension control system

Web tension control systems have a structure of multi-inputs and multi-outputs consisting of many subsystems. Those subsystems are divided into two main groups of systems such as tension control and speed control systems, and have strong interactions between neighboring subsystems through the associated web tensions. The decentralized controller of each control station attached to a subsystem is expected to control the output according to the reference regardless of the interactions. This paper shows some control strategies to compare the performance and to study the decentralized control concept. Two methodologies for designing the controller are presented. One is a high gain adaptive control scheme, and the other is an H-infinity control scheme where a new weighting function is introduced to obtain global stability. From a computer simulation, each benefit for the control strategy is discussed.

Decentralized controller design of web tension control system in terms of interactions

A web tension control system has a structure of multi-inputs and multi-outputs with strong interconnections, with decentralized information processing. The interactions among the input signals should be estimated sufficiently to assure appropriate stability and performance of the decentralized control system. This paper shows some guidelines for designing the decentralized web tension control system with a disjoint decomposition structure. The interactions are viewed with a technique of interaction measures. The guidelines for PI controller design are described based on those calculated results.

Decomposition and Decentralized Controller Design of Web Transfer System

Abstract This paper describes a web tension control system as one application area of large-scale system control theory. We show its typical structure, how it works, and the modeling method at the first part of the paper. It is pointed out in the next section that a disjoint decomposition may deteriorate the control performance due to the mutual interactions, and the overlapping decompositions could improve the performance. And then, some interaction measures, which are estimated in terms of the controlled object and the closed loop system, are demonstrated to see how the difference of decomposition is reflected in the calculated results of the interaction measures.

Induced currents and forces for the split-guideway electrodynamic levitation system

A three-dimensional integral equation formulation of the electrodynamic interaction of an array of superconductive magnets moving over a pair of conducting guideway strips is reviewed. The induced current distribution in the split-guideway conductors and the lift, drag, and lateral forces are presented, and the effects of vehicle speed, lateral displacement, and gap between the guideway strips on levitation characteristics are discussed. >

Decentralized Control Performances of an Experimental Web Handling System

Robust and good tracking control of the speed and the tension in web handling systems in spite of changes of set point is surely one of the important challenges in the web transport systems future development. In this paper, the authors experimentally demonstrate the real applicability of a decentralized robust control to a multi-span web transport system, which is composed of twelve guide rollers, four main sections mutually interconnected with each other. The overlapping methodology has been applied for the system decomposition. The experimental results carried out using the robust decentralized control show an excellent velocity and tension tracking in each controlled section of the system.

Decentralized H∞ based control of a web transport system

Abstract Robust and good tracking control of the speed and the tension in web handling systems in spite of perturbations such as changes of web material is surely one of the important challenges in the web transport systems future development. In this paper, the authors experimentally demonstrate the applicability of a decentralized robust control to a multi-span web transport system, which is composed of eleven guide rollers, four main sections mutually interconnected with each other. The overlapping methodology has been applied for the system decomposition.

Linear model validation for controlling a multi rollers high speed web system

In this paper the authors describe the linear model validation strategy based on experimental tests of a new complex multi-roller web systems specially powered for running with high web speeds. The problem of validation has been dealt in using an optimization strategy for the estimation of several unknown model parameters. The experimental tests show the validity and accuracy of the procedure.

Interaction measures for the decentralized tension control system

In a web tension control system, the mutual interactions between the control stations is the major problem when designing a control system. The information structure can take two forms: (a) decentralized control with disjoint information structure, or maybe called nonoverlapping decomposition structure, and (b) decentralized control with overlapping decomposition. The paper discusses the controller design guidelines with the mutual interaction analysis for these forms of control structure. The paper discusses the controller design guidelines for decentralized web tension control system with the aid of some forms of interaction measures and the modeling concept. We first suggest how to determine the subsystems used for controller design. The analysis contains four ways for evaluating the interactions, which cover two concepts of stability and output error behind the formulations. It is made clear how the interactions work in terms of frequency.