| A new control algorithm, wavelet-hybrid feedback LMS algorithm, is developed to overcome the shortcomings of the classical feedback control algorithms and the filtered-x LMS control algorithm. It integrates a feedback control algorithm such as the LQR or LQG algorithm with the filtered-x LMS algorithm and utilizes a wavelet multi-resolution analysis for the low-pass filtering of external dynamic excitations. Since the control forces determined by the filtered-x LMS algorithm are adapted by updating the FIR filter coefficients at each sampling time until the output error is minimized, the new control algorithm is effective in control of both steady-state and transient vibrations. It is shown that the algorithm is capable of suppressing vibrations over a range of input excitation frequencies unlike the classic feedback control algorithms whose control effectiveness decreases considerably when the frequency of the external disturbance differs from the fundamental frequency of the system. Further, results demonstrate that the wavelet transform can be effectively used as a low-pass filter for control of civil structures without any significant additional computational burden.; A new hybrid control system, hybrid damper-TLCD system, is developed through judicious integration of a passive supplementary viscous fluid damping system with a semi-active TLCD system, and its performance is evaluated for control of responses of 3D irregular buildings under various seismic excitations and for control of wind-induced motion of high-rise buildings. The new hybrid control system utilizes the advantages of both passive and semi-active control systems along with improving the overall performance and eliminating the need for a large power requirement, unlike other proposed hybrid control systems where active and passive systems are combined. Simulation results show that the new hybrid control system is effective in reducing the response of structures significantly under seismic excitations as well as wind loads. It is also demonstrated that the hybrid control system provides increased reliability and maximum operability during normal operations as well as a power or computer failure. |
