HEURISTIC-BASED ALGORITHM FOR ACTIVE CONTROL

A simple effective control algorithm, free from the problem of time de lay, is proposed. It is a closed-open loop control. The control force is applied to the structure at the current time to cancel the portion of the system velocity that is induced by the response and the externa l load at the preceding time step. This control concept is motivated b y the fact that, for a single degree of freedom (SDOF) structure subje cted to external loadings, the energy of the external load is imparted to the structure by changing the structural velocity. A simple, close d-form equation is used to compute the control force for SDOF systems, and for multiple degree-of-freedom (MDOF) systems, it is used in conj unction with the mode-superposition method. Numerical examples are use d to demonstrate the effectiveness of the proposed control algorithm. A strategy for coping with the spillover effect is also proposed. The results of the examples show that the proposed control algorithm can r educe the maximum structural response by one order of magnitude and ha s the ability to reduce the peak that occurs during the first few cycl es of the time history, an ability that linear control laws lack. Unli ke most control algorithms that deal with the state space of the syste m that usually involves complex-valued eigenvalues and eigenvectors, t he proposed control algorithm deals with the real-valued normal modes of the system.