In this paper, a semiactive isolation system is proposed mainly from the veiwpoint of anti-seismic design of mechanical structures, equipments in industrial facilities including nuclear plants. Mechatro Damper proposed in this work has a structure as shown in Fig.1. When axial thrust excitation is given from right hand side, this motion can be translated into rotational motion by the ball screw mechanism. This rotational motion is accelerated by the gear amplifyer and then rotation of D.C. servo motor is generated. Damping force of Mechatro Damper can be produced by electric energy induced by the D.C. motor. The key advantage of this isolator is found out in the controlability of this damping force. Damping control is achieved by using "discrete time sliding mode control algorithm". Firstly, in this work, mechanical simulation is carried out by applying above mentioned control algorithm. Compared with the results for passive control cases, those for semiactive control provide dominant damping effect abound resonant frequency range as well as higher frequency range. Secondly, excitation test is executed by shaking table to the experimental Mechatro Danper device. Through this test, it is made clear that switching time lag required to the sliding mode control operation is highly sensitive to the controlability of this damper. Characterristics obtained from the simulation are quite well recognized through the experiment.
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