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

Active vibration control is an important problem in structures. One of the ways to tackle this problem is to make the structure smart, adaptive and self-controlling. The main objective of active vibration control is to reduce the vibration of a system by automatic modification of the system's structural response. This work features the modeling and design of a robust decentralized controller for a smart flexible system using a periodic output feedback control technique when there is a failure of a system component to function (say, an actuator). The entire structure is modeled in state space form using the finite element method and Euler-Bernoulli theory principles by dividing the master structure into eight finite elements and placing the piezoelectric sensor/actuators as collocated pairs at finite element positions 2, 4, 6 and 8, thus giving rise to a multi-input multi-output plant. Robust decentralized periodic output feedback controllers are designed for the various models of the plant, retaining the first two vibratory modes and considering one actuator failure at a time. The effect of failure of one of the piezopatches on the system is observed. In this control law, the control input to each actuator of the multimodel flexible system is a function of the output of that corresponding sensor only and the gain matrix has all off-diagonal terms zero. The designed robust decentralized periodic output feedback controller provides satisfactory stabilization of the multimodel smart structure system