Design of Modal Control of Structures

A structure with active control possesses a mechanism to apply forces on the structure by prestressing cables or other suitable devices to reduce the structure response. This mechanism is controlled by current or voltage produced by sensors located at various points of the structure, and this current or voltage is related to the response of the structure at the sensor location. The modal approach is a technique for designing this mechanism. When using the modal technique, the effect of the active control mechanism on the structure response can be presented by the so-called influence matrix. This matrix indicates the effect of the active control mechanism on the different modes of the structure. By studying the properties of this matrix, the effect of changing parameters in the active control mechanism on the response of the structure can be seen clearly and the matrix can be of great help in the designing of the active control mechanism.