Negative imaginary systems in control engineering: a bibliometric perspective

This study analyzes the scientific production related to the theory of control in negative imaginary (NI) systems through a bibliometric analysis in the Web of Science (WoS) and Scopus databases. The main purpose is to evaluate the research output, identify key trends, and map the research landscape in NI systems. The significance of this analysis is rooted in the ability of NI system theory to improve the robust control of resonant and dynamic systems, making it applicable across various engineering disciplines. The methodology involves specific search configurations, data collection and unification (2004–2024), and cleaning and preprocessing tasks. A classification algorithm is implemented to compare and detect duplicate titles between both scientific databases, followed by a quantitative analysis and visualisation of results. Finally, the results are mapped and interpreted to identify key trends and patterns in the emerging areas of the NI system. The results indicate significant growth in scientific production, with applications ranging from nanotechnology to robotics. Advances in the characterisation and robustness of NI systems and data-driven control synthesis methods have paved the way for their adoption as solid theory in control systems. Recent extensions of non-linear systems underscore their innovative potential, versatility, and relevance in complex system control engineering.