tailieunhanh - An extension of the identification algorithm for feedback active control of incomplete measured systems

A previous paper, the identifi cation algorithm is presented for feedback active controlled systems. However, this method can only be applied to complete measured systems. The aim of this paper is to present a combination of the identification algorithm and the modal superposit ion method to control the incomplete measured systems. | V ietnam Journal of Mechanics, VAST , Vol. 30, No. 1 (2008) , pp. 33 - 42 AN EXTENSION OF THE IDENTIFICATION ALGORITHM FOR FEEDBACK ACTIVE CONTROL OF INCOMPLETE MEASURED SYSTEMS LA D ue VIET , NGUYEN DONG ANH Institut e of Mechanics Abstract. !11 a previous paper [l], the identi fi cation algorithm is presented for feedback active controlled systems. However , t hi s method can only be applied to complete measured systems. The aim of this paper is to present a combinat ion of the identification algorithm a nd t he modal superp osit ion method to control the incomplete measured systems . The system response is expanded by modal eigenfunct ion technique. The external excitation acting on some first modes is identified wit h a t ime delay a nd wit h a small error depending on the sensor locat ions. Then the control forces will be generated to bala nce the identified excitat ions. A numeri cal simulation is a pplied to an eight story building sub jected to base acceleration. 1. IN TRODUCTION The active control m ethod can be applied to many problems such as robot control, ship autopilot , airplane autop ilot , vibration control of vehicles or structures . F ig. 1 provides a schematic diagram of an active control system. Sensors Computer, control algorithm Sensors Actuators, Control forces Excitations J_. Controlled system Responses Fig. 1. D iagram of a structural control system It consists of 3 main parts: sensors to measure either external excitations or system responses or both ; computer controller to process the measured information and to compute necessary control force based on a given control algorithm ; actuators to produce t he required forces . When only the responses can be measured , the met hod is called feedback active control. In recent years , t he act ive control method has been widely used to reduce the excessive vibrations of civil struct ures due to environmental d isturbances ([2]) . One of the bas ic tasks of active structural

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