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This paper deals with a novel type of semiactive damper which is composed of a cylinder injected with Magnetic Rheological Fluid(M.R.F.) and an electromagnet with a nonlinear [H.sup.[infinity]] controller. It is generally known that the viscosity of M.R.F. depends on the magnitude of a magnetic field. Therefore this paper aims at controlling the damping property of a mechanical system by changing the magnitude of magnetic field. In this study, the novel semiactive damper system is modeled precisely, next a designing method of the [H.sup.[infinity]] nonlinear controller is proposed and finally various advantages of the proposed damper system are confirmed by digital simulations.

Recently, the noncontact conveyance methods that are applied magnetic levitation techniques have been studied in many institutes. In this paper, from the view point of practical use, the authors construct a magnetic levitation system without using gap sensors which have been essential for the conventional magnetic levitation of thin steel plates. This system adopts both current sensors and Hall‐effect sensors in place of the gap sensors. In addition, we consider the peculiar inductance characteristics of magnetic levitation for a thin steel plate. Moreover, we conduct the levitation, guidance, conveyance and disturbance experiments. [ABSTRACT FROM AUTHOR]

Adoption of magnetic levitation techniques for production lines of steel plates has many advantages such as simplification of machining processes and improvement in quality of products. However, conventional levitation [1] procedures have not solved the problem for thin steel plates of sideslipping caused by gravitational force. In this paper, the following idea is proposed in order to avoid sideslip: The gap length command between the steel plate and the electromagnet is corrected so as to levitate the plate horizontally. Various experiments are performed under the proposed control, in order to confirm the validity. Index Terms--Guide control, horizontal control, MAGLEV for thin steel plates.

This paper deals with a novel type of semi active damper, which is composed of a cylinder injected with Magnetic Rheological Fluid(M.R.F.) and an electromagnet with a nonlinear [H.sup.[infinity]] controller. It is generally known that the viscosity of M.R.F. can be changed by the magnitude of a magnetic field. Therefore, this study aims at constructing such a semi active damper system that makes good use of the property. A flow for controlling the semi active damper system is as follows. First, if an electromagnet current is changed, the magnitude of the magnetic field generated by the current is changed. Next, the viscosity of M.R.F. is also changed by the magnetic field. Thus, the motion of a piston set under the M.R.F. is controlled. As these results, an overall equivalent damping coefficient in the semi active damper system can be controlled by the electromagnet current. In the former paper[1], a theoretical model of the novel semi active damper was proposed. Next, a designing method of the [H.sup.[infinity]] nonlinear controller for this type of damper was shown. Finally, some advantages of the proposed semi active damper were confirmed only by digital simulations. This time, a semi active damper is made and its properties are measured. In addition, a suitable nonlinear compensator for the M.R.F. damper is installed, various vibration experiments are carried out and many interesting results are reported. Index Term -- Semi active damper, magnetic rheological fluid, [H.sup.[infinity]] nonlinear control, vibration experiments.

In the previous paper 1, a novel type of semi-active damper that is composed of a cylinder injected with Magnetic Fluid (M.F.) and a magnetic flux controller was proposed for improving the ride comfort of trains. In this paper, at first, a modified model considering nonlinear characteristic of M.F. such as a Non-Newtonian-Fluid is proposed. Next, in order to enhance the control effects, two kinds of improvements are made in the semi-active damper. One is to change the voltage control input to an electromagnet into the current control input. The other is to expand the control range for the M.F. damper by means of feeding a bias current to the electromagnet. Finally, the effects of the improved semi-active damper are shown by various digital simulations and vibration experiments. [ABSTRACT FROM AUTHOR]

In the process line of a strip belt, it is desirable to reduce contacts between rollers and steel strips to produce better quality. In addition, it is also desirable to hold the shape or to suppress vibration with as little contact as possible. This paper proposes a model apparatus for controlling vibration without any contact. It aims to use economic and compact current-sensors instead of expensive gap ones and also the controlled attractive force of electromagnets. This paper investigates the effects for the several types of vibration control effects for the strips by digital simulations and experiments. [ABSTRACT FROM AUTHOR]

Magnetically levitated railway system is receiving increased attention all over the world due to its features of low noise and easy maintenance. It was put into practical use in England to connect an airport with a city 600 miles away. TR-60 is running on an experimental line 20 km long in Emusland, West Germany. HSST of Japan Air Line was demonstrated on the curved rail at the World Fair in Vancouver, Japanese National Railway is also running an experimental line in Miyazaki. The magnetically levitated railway using normal conducting magnetics has a disadvantage (in comparison with the railway using superconducting magnets); it is difficult to widen the air-gap length. The amount of energy required to maintain levitation can be reduced by decreasing the air-gap length. In practice, including the response characteristics to the rail discontinuity at rail joints and height different due to cant. This paper discusses the features and control methods of twist response type electromagnetically levitated truck and presents its digital control performance. [ABSTRACT FROM AUTHOR]

This paper discussed the behavior of coupled rail cars running on flexible rails by digital simulation and studies the relations between running speed, cutoff frequency of levitation system, number of coupled cars and rail mass. Discussion is also made on how to evaluate the damping effects of the proposed control circuit. Levitating magnets mounted on the bogie truck control the car position following the rail surface and the secondary suspension between vehicle and bogie truck controls the quality of the ride. Since each of the two bogie trucks supports the vehicle through two secondary suspensions, the vehicle is able to run very easily along curved rails. Levitating magnets are mounted on the trucks and therefore the space under the vehicle is utilized very effectively. Assuming that a pair of left and right levitating magnets support the vehicle at one point, each vehicle is supported on two bogie trucks at four points in all. If N vehicles are coupled together, the rails and Levitating magnets is very important. Control of Levitate railways taking into account the stiffness of rail has been discusses a similar problem from th viewpoints of damping characteristics of rail and running characteristics of coupled rail cars. [ABSTRACT FROM AUTHOR]

Focuses on the research on a normal conducting magnetically levitated vehicle on rails considering rail oscillation. Suppression of the rail oscillation effectively using the 5th degree control system over the practical speed; Effectiveness of the control schemes by simulation.