Closed loop structural control using electrorheological dampers

Electrorheological (ER) dampers are attractive in control applications where external power cannot be guaranteed. ER dampers are inherently nonlinear, and the sign of the damper force is constrained by a passivity condition. Idealizing these nonlinearities and using a Lyapunov-based control synthesis leads to a bang-bang control rule which minimizes the rate at which the energy from the disturbance is transmitted to the structure. This control rule is applicable to linear and nonlinear structural systems. Simulation results of a bilinear hysteretic structure disturbed by earthquake ground motions, and controlled by modulating the electric field in an ER device, illustrate the control performance. The primary effect of the control is to attenuate peak responses in the early seconds of the earthquake.