The aim of the paper is to present a control law for feedback active controlled structures in which a control algorithm is proposed to identify the external excitition with a time delay. The time duration in which the external excitation acts on the structure is devided into subintervals | VJtnam Journal of Mechanics, NCST of Vietnam Vol. 22, 2000, No4 (193 - 204) AN IDENTIFICATION ALGORITHM FOR FEEDBACK ACTIVE CONTROL NGUYEN DONG ANH Inst£tute of Mechanics, NCST of Vietnam I ABSTRACT. The aim of the paper is to present a control law for feedback active cont rolled structures in which a control algorithm is proposed to identify the external excitJtion with a time delay. The time duration in which the external excitation acts on the strJcture is devided into subintervals. In each subinterval the external excitation is identified and is then selected with the opposite sign as the control force for the next subinterval. The realization of the identification control algorithm in the practical application mainly deIJends on the computing capacity of the involved computer. and requires an investigation with respect to its robustness and stabilization. I 1. Introduction In recent years much progress and new concepts have been archieved in the development of structural control in reducing the response during excessive vibrations due to environmental loading Casciati et al. [2], Housner et al. [6 ], Kobori [7]. The !c ontrol of structural motions can be done by various means. Among them passive J nd active control systems represent fundamental approaches in the use of control strategies for response reduction in structures. The first approach proposes to reduce the energy of the environmental disturbances acting on the structure by transferrli ng its part in to other structural elements (secondary systems), while the latter usi s the control counterforces produced by actuators to balance the environmental loading. Since in the first approach the structure does not receive any additional energy, the application of passive devices is usually effective up to a certain limit. A major disadvantage of the second approach is that in many cases of practihal interest, the required additional forces are too large existing actuators (for exailiple, the case of .
