Decoupling loading effect in simultaneous sensing and actuating for dynamic measurement

When doing dynamic measurement using an electromechanical transducer for both sensing and actuating simultaneously, loading effect of the transducer is obviously large enough to jeopardize measurement accuracy. This paper examines the role of a newly introduced 'transduction matrix' in decoupling the loading effect from a piezoceramic inertial actuator (PIA) which is employed to detect pseudo mechanical impedance of a structure as both exciter and sensor simultaneously. The two by two transduction matrix characterizes the relationship between the input electrical variables and the output mechanical variables of the PIA. Once it is properly calibrated, the mechanical impedance of the structure can be indirectly detected via measuring the input electrical impedance of the actuator. In this presentation, the appropriateness of a numerical model of the PIA is first validated through comparison with experimental results. Then, the influences of design parameters of PIA on its transduction matrix as well as measurement accuracy are studied numerically in detail. The results show that, although the transduction matrix varies significantly due to changes of design parameters, the detected mechanical impedance remains the same for a given structure, as the loading effect of the PIA is satisfactorily decoupled.