Fault tolerant control of flexible smart structures using robust decentralized periodicoutput feedback technique

Abstract

Active vibration control is an important problem in structures. One of the ways to tacklethis problem is to make the structure smart, adaptive and self-controlling. The mainobjective of active vibration control is to reduce the vibration of a system by automaticmodification of the system’s structural response. This work features the modeling anddesign of a robust decentralized controller for a smart flexible system using a periodicoutput feedback control technique when there is a failure of a system component tofunction (say, an actuator). The entire structure is modeled in state space form using thefinite element method and Euler–Bernoulli theory principles by dividing the masterstructure into eight finite elements and placing the piezoelectric sensor/actuatorsas collocated pairs at finite element positions 2, 4, 6 and 8, thus giving rise to amulti-input multi-output plant. Robust decentralized periodic output feedbackcontrollers are designed for the various models of the plant, retaining the firsttwo vibratory modes and considering one actuator failure at a time. The effectof failure of one of the piezopatches on the system is observed. In this controllaw, the control input to each actuator of the multimodel flexible system is afunction of the output of that corresponding sensor only and the gain matrix has alloff-diagonal terms zero. The designed robust decentralized periodic output feedbackcontroller provides satisfactory stabilization of the multimodel smart structuresystem.