Enhancing active vibration control of pedestrian structures using inertial actuators with local feedback control

Active vibration control (AVC) via inertial actuators is considered a viable technique for the mitigation of excessive vibrations in civil engineering structures. In particular, several recent field trials have shown that this technique has the potential to be effective for the cancellation of human-induced vibrations in pedestrian structures. However, prior to the implementation of AVC using inertial actuators, several drawbacks have to be dealt with. The main disadvantages come from the dynamic behaviour of the inertial actuators employed for this application, which are: (i) their low frequency dynamics (that might interact with the structure dynamics), and (ii) their nonlinearities (stroke and force saturation). Thus, any control technique to be implemented has to tackle stability problems (caused by the low frequency response of the actuators) and stroke and force saturation, which might lead to poor vibration cancellation performance. To alleviate such drawbacks, this work proposes to use an AVC strategy based on two control loops: (i) a loop, closed within the actuator, designed to artificially modify the actuator frequency response according to its maximum stroke and force and the structure dynamics, and (ii) a loop designed to impart damping to the structure. This work focuses on the design process such that stability and actuator saturations are taken into account to improve the efficiency of a given inertial actuator when the AVC system is based upon velocity feedback. Experimental results on a full-scale concrete laboratory structure using a commercial actuator are presented to illustrate the performance of the AVC strategy proposed, which ensures adaptability to a given structure without requiring hardware modifications.