Experimental control of free and forced structural vibration using a linear coupling strategy

Abstract

In this work we further develop the energy-based control strategy `linear coupling control (LCC)' for controlling free and forced vibrations in flexible structures. The control strategy is implemented by coupling a virtual second-order linear system (controller) to an oscillatory plant and creating an energy exchange between the two systems. The energy transfer phenomenon between the two oscillators is maximized by coupling the appropriate states of the plant and the controller. Once energy is transferred from the plant to the controller it is dissipated via linear damping. The experimental verification of this approach to vibration suppression is presented for the cases where it is undesirable to add actuators with significant mass and stiffness to the structure. The virtual controller is built into a personal computer with a clock rate of 100 MHz. Matlab software, Real-Time Workshop Toolbox, WatCom compiler, and WinCon software in conjunction with an analog - digital/digital - analog card are employed to implement the control law. The experimental results have shown the controller's potential to eliminate free and forced vibration. In forced vibration the energy coupling control law provides over 98% reduction of the steady state amplitude. In previous research using the LCC method documented only once prior to this paper, the controlled forced responses have shown, at best, an 80% improvement in amplitude over the uncontrolled responses. A comparison between the proposed controller and the classical state-feedback controller shows significant advantages of the LCC method. Finally due to the nonlinear behavior of the piezo ceramics, a dynamic deflection test is performed to derive the effective range of piezo actuators.