Effect of actuator dynamics and fixed time-delay on the stability of actively controlled structures

The total time-delay in a structural control system consists of a fixed time-delay due to processing of signals and an actuator build-up time-delay. In this paper, a closed-form stability analysis is presented to investigate the effect of total time-delay on the performance of a controlled structure, i.e., the fixed time-delay is not compensated whereas the actuator dynamics is neglected. Numerical results show that the controlled structure is stable only in a certain region of velocity and displacement gains. This region of stability reduces with an increase of the fixed time-delay. Further, the performance of the controlled structure degrades significantly when the ratio of actuator and structural frequencies is in the range of 5 to 10