Experiments in piezostructure modal analysis for MIMO feedback control

An approximate method for modal analysis of a piezostructure testbed is used to generate a dynamic model for closed-loop, multiple-input-multiple-output (MIMO) feedback controller design. An innovative pole-residue system model for structures instrumented with piezoelectric sensor and actuators is developed which is compatible with existing modal curve-fitting algorithms. The authors examine the use of the new pole-residue model in the absence of truly collocated response information. It is shown that nearly-collocated measurements may be used to estimate a structure's modal parameters; high-precision signal conditioning electronics required for exact drive-point response measurements are thereby avoided. A simply-supported plate is used to demonstrate the approximate piezostructure modal test approach. The test model is then used to design up to a four input, sixteen channel output MIMO feedback control experiment. Closed-loop results are presented which show that more than 10 dB of suppression is achieved near structural resonances within the control bandwidth (10-250 Hz).