# State-of-the-Art Review of Structural Vibration Control: Overview and Research Gaps
## 6 Optimized Control System Designed to Tackle Practical Implementation Challenges
### Control Systems to Ensure Robustness to Uncertainties
This approach enables the controller to adapt to changing system dynamics by updating its rule base and membership functions over time, resulting in enhanced control accuracy and robustness. It is observed that the use of frequency domain control methods involves analyzing and designing control systems in the frequency domain, where the behavior of a system is examined in terms of its response to different frequencies. H\({}_{\infty}\) control is one such method that is often used for robust control system design, particularly in the presence of uncertainties and disturbances. Robust H\({}_{\infty}\) control seeks to minimize the impact of disturbances on the controlled system while maintaining stability and optimal performance. It provides a framework for handling uncertainties and disturbances to optimize the system's response in the presence of these factors. Studies have also shown that the use of frequency-shaping filters incorporated into the control system influence or shape the system's frequency response. These filters allow us to tailor the system's behavior at specific frequencies, making it more responsive or less sensitive to specific input frequencies. [PERSON] and [PERSON] [165] developed a novel control algorithm based on H\({}_{\infty}\) for a variable friction-based semi-active control system. The controller was designed to determine the optimal control force for reducing responses to near-fault earthquakes. The study's results, considering stiffness uncertainty, indicate that both active and semi-active H\({}_{\infty}\) controllers demonstrate robustness and effectiveness in reducing responses for intelligent base-isolated structures in the face of near-fault earthquakes. [PERSON] et al. [192] conducted an experimental validation of wireless communications for real-time structural control, assessing the control performance of the wireless system in comparison to a conventional tethered control system. The efficacy of the wireless control system is evaluated through a shaking table test performed on a three-story steel frame equipped with an MR damper on each floor. The study demonstrates that wireless sensor networks represent a promising technology capable of operating in real-time environments. Additionally, the study highlights the advantages of decentralized control approaches due to their robustness against failure, ensuring that the control system can still operate even if one damper fails to function correctly. [PERSON] et al. [107] studied the mechanical performance of a piezoelectric ceramic friction damper installed on a three-story structure. An adaptive fuzzy neural network controller (FNNC) is proposed, and its performance is compared with the LQR optimal control. To study the robustness and stability of the proposed controller in the presence of model uncertainties, a stiffness adjustment of \(\pm\)10% is considered. The results indicate that FNCC exhibits good robustness and stability, particularly in the face of uncertainty, and can effectively reduce the responses.