Development and performance evaluation of a robust suboptimal H∞‐based proportional–integral controller–observer system with target tracking for better control of seismic responses

In this article, a new full‐ and reduced‐order proportional–integral (PI) controller is developed such that the target‐tracking or command‐following problems become generic for a wide range of frequency inputs. The proposed controller has been developed for better control of seismic responses of structures. The integral part of the proposed controller in this case is formulated by proper factorization of relevant components in closed loop to avoid the presence of uncontrollable poles in the feedback system. Further, the controller–observer framework is designed through suboptimal H∞ control algorithm. The robustness and stability of the algorithm are evaluated in terms of tracking a wide range of frequency inputs, while mitigating the influence of sensor noise and modelling uncertainties at the same time. The efficiency of the proposed PI controller is established with respect to the suboptimal H∞ ‐based proportional controller in terms of reduction in error signal of a nominal and perturbed single degree‐of‐freedom spring–mass–damper system. Further, the applicability of the proposed controller in a realistic scenario is studied using a base‐isolated building under strong seismic excitation. The performance of the control algorithm is evaluated in terms of isolator displacement, inter‐storey drift and top‐floor drift of the nominal model. The results from this work highlight that the proposed controller has significant potential for practical implementation in civil engineering structures.