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This paper describes static loading tests results of earthquake isolation system using vertically utilized coiled springs and discusses analytical model for elastic coiled springs. The static loading tests were carried out for two types of elastic coiled spring in which had a different material SUP 9 and SUS 304 stainless steel. The elastic coiled springs were designed to provide a 10 000 kg rated mass with a horizontal natural frequency about 0.20 Hz and that they could accept a displacement of about 200 mm or more. Fundamental characteristics of the elastic coiled springs such as transverse stiffness of coiled spring and the effects of the restoring force characteristics by the difference between the pressurization directions were clarified through the static tests. These characteristics of transverse stiffness of elastic coiled spring were analyzed using simple model good results were obtained.

This paper describes the research and development of the new type of isolation systems suitable for light-weight-houses. The Basic concept of the new isolation system is to realize cost effective design without any reduction in the isolation performance. This paper presents results obtained from experimental and analytical studies to evaluate isolation performance of the new isolation system. In the experiment, static tests were first carried out using a 0.20 scale model (55kg mass, and 0.50m × 0.50m × 0.27m size) for isolated-light-weight-houses model which was supported by two linear ball bearing and, restring force was given to superstructure by transversal stiffness of a coiled spring, so as to examine restring force characteristic for the coiled spring. Second, dynamic tests were implemented in order to investigate the isolation performance of the isolation system in actual seismic waves. In analysis, seismic response analyses for the scale model, regarding the vibration tests using the actual seismic wave, were carried out to evaluated the response analytical method for the isolation system using the coiled spring. From these results, the following are clarified. (1) Analytical results for the isolated-light-weight-houses model agree well with experiment results. (2) The isolated system using the coiled spring reduced responses acceleration sufficiently.

This paper proposes a reduced-order physical modeling method for controlling the multi-modes of vibration of an active isolation system with an elastic table. In the lightweight isolation table, the elastic modes appear on the isolation table in a lower frequency domain. In order to avoid the spillover phenomena, the reduced order model, which includes elastic modes, is used in this modeling method. In this study, a reduced order physical model, expressed by 5DOF systems for controlling the multi-modes for designing the controller, LQ control systems, and a two-degree-of-freedom control method with feedforward control are applied. Finally, the discrete model and the controller design are verified through numerical calculations and experimentation.

Microtremor isolation is important for improving the yield rate of complete IC chips. For this purpose, passive isolation devices using air springs have been used so far. However, as the degree of integration in IC chips increases and patterns of circuits become more fine, more complete isolation is becoming necessary. Therefore an active isolation system using linear motors was developed, in which the table supported by air springs was controlled by 4 vertical linear motor actuators and 4 horizontal linear motor actuators. The isolation system used a full-state feedback control system designed by the optimal regulator theory. The controller, implemented by a 16-bit personal computer, calculated 8 control inputs to the actuators from 12 signals made by integration of absolute accelerations detected by sensors, 6 of which were absolute velocities and the other 6 of which were absolute displacements. Through tests, it was confirmed that the active system could achieve superior performance compared with a passive system with high performance.