Gain-Scheduled Vibration Isolation Control Using Semi-Active Actuator

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I have examined a modelling of a semi-active actuator with a variable damper mechanism and have constructed the new damper model whose damping coefficient is assumed to be linearly changed by the variable valve mechanism, where the servo valve can adopt the orifice open rate. I assume that the valve displacement is restricted by a nonlinear spring. The damper model has been applied to a vehicle suspension and I have introduced the linear parameter varying system involving the variable damper model. Thus, I have designed the gain-scheduled control system and it has been verified from simulation results that the damping coefficient is smoothly changed according to the state of the suspension and the proposed controller can perform the specified control.Furthermore, I have applied the proposed method to a Magneto-Rheologial fluid damper. The characteristics of the MR damper were identified as the relation between input current and damping coefficient. I approximated the relation as the function of the one fifth power of stroke velocity. And I have designed the control system that put the input current to the MR damper, so that the MR damper coefficient coincides with output from the proposed gain-scheduled controller. By carrying out experiments effectiveness of the proposed method has been verified. Also it has been verified that a Kalman filter I designed can estimate the stroke velocity.I have also examined application of the semi-active control system to a four-degree-of-freedom structure. I designed the proposed control system for the reduced-order model. It has been verified from simulation results that the proposed method can suppress the vibration when the variable range of damping coefficient is relatively small. I have found out excitation problem of the higher modes by switching of the controller with sign of the stroke velocity in case that the variable range becomes large.