Multivariable adaptive vibration control of smart structures using iterative (LQG) control strategies

This paper presents experimental adaptive identification and control of a smart structure featuring piezoceramic based sensors/actuators. An inverted L structure with surface bonded piezoceramic sensors/actuators is used for analysis, and the state-space presentation, from control input voltages to output sensor voltage, is established in multivariable form. A multi-input multi-output (MIMO) linear quadratic regulator (LQR) is designed for a unique canonical form. It is assumed that the parameters of the smart structure are changing. Closed-loop, time domain identification of system parameters in auto-regressive moving average (ARMA) form is proposed for systems changing at slow rates. Other transformations are discussed to convert the system of difference equations to canonical state-space form and vice-versa, so that the LQR can be redesigned on-line, for identified, changing parameters of the flexible structure. A thorough study is done to see the effect of updated system parameters and control gains.