Adaptive Feedback–Feedforward Control of Building Structures

This paper proposes a combined feedback–feedforward control algorithm for reducing structural response of buildings to seismic excitations. The controller contains both feedback and feedforward components. The feedback component is assumed to be the same as that found from traditional linear quadratic regulator design. The feedforward component is obtained by estimating the external excitation as a series of step functions at each time increment. This feedforward gain varies with the duration of the step function used for estimation and converges as the time duration increases. Thus, a finite number of precalculated gains can be used to represent the potential feedforward gain profile. At any instant in time, the excitation is measured and by using the past measurements, the most effective feedforward gain for the recorded excitation values can be selected from the set of precalculated gains. This value is used as the feedforward gain for the current time step. Numerical examples are presented to show the effectiveness of this adaptive control scheme. The effects of varying the control objectives, the updating time for the feedforward gain, and the number and location of actuators are studied.