Application of fuzzy set theory to the active control of base-isolated structures

Fuzzy techniques are employed for the nonlinear control of sliding-isolated structures. Base isolation of structures that are subjected to seismic excitation has been shown to be effective in reducing the forces transmitted to the superstructure. Active control, using linear control laws, applied to supplement the base isolation has proved to be effective in reducing the transmitted forces further. However, the response of a base-isolated structure is nonlinear and nondeterministic. Hence nonlinear control laws that accommodate uncertainty would yield better reduction of these forces. Fuzzy set theory and fuzzy logic provide a simple framework for specifying these complex control laws. The results obtained with the fuzzy algorithm are compared to the analytical and experimental results obtained using an instantaneous optimal control algorithm. The results demonstrate the potential of the fuzzy algorithm when applied to the hybrid control of structures