A Regenerative Force Actuation (RFA) Network consists of multiple electromechanicalforcing devices distributed throughout a structural system and actuated in such a way as to reducethe response of the structure when subject to an excitation. The associated electronics of thedevices are connected together such that they are capable of sharing electrical power with eachother. This makes it possible for some devices to extract mechanical energy from the structure,while others re-inject a portion of that energy back into the structure at other locations. Theforcing capability of an RFA network is constrained only by the requirement that in the aggregatethe total network must always dissipate energy.The electromechanical currents generated by RFA networks must be controlled to createthe desired structural forces. This control is facilitated by the alternation of a multitude of powerelectronictransistor switches in the electrical network. In this study, a sliding-mode switchingcontroller is proposed for realizing zero-error force command tracking. It is shown thatparameter uncertainty is a critical issue for force commands which require the network to operatenear its optimum transmissive efficiency.RFA networks can be used to create velocity-proportional damping forces in structures.However, unlike traditional structural damping, RFA networks have the ability to create non-localand asymmetric damping forces. It is shown that this more generalized damping capability canlead to significant improvements in the forced response of a structure, as compared withtraditional linear damping.RFA networks may also be used for feedback control. In this context, the forcingcapability of the RFA network is constrained by its physical limitations. In this study, asystematic method of nonlinear control design called "Damping-Reference" control is proposed,which guarantees a certain level of quadratic performance for the structural response. Variants ofthe control law synthesis are proposed for quadratic regulation, stochastic control, and H∞ controlcontexts.These ideas are illustrated in the context of earthquake engineering through a simulationexample, involving a three-story structure with a two-actuator RFA network installed. In thisexample, it is shown that the "power sharing" nature of the RFA network has a significantinfluence on the response.
展开▼
