Effects of control-structure interaction in active mass driver systems with electric torsional servomotor for seismic applications

Active control systems are a viable solution to mitigate seismic effects in buildings. The actual response of structures equipped with active control devices is influenced by control-structure interaction (CSI) and actuation imperfection. This paper investigates both effects on the response and on closed-loop stability of a frame structure equipped with an Active Mass Driver with electric torsional servomotor. The closed-loop stability conditions are studied by investigation of the root-locus of the system and the effects of CSI and actuation imperfection are individually quantified. Results obtained under harmonic and seismic base excitations show that accounting for CSI leads to non-negligible variations in control performance, especially for large mass ratios, and that actuator's dynamics significantly influence the system's stability.