English

Finding the Nearest Negative Imaginary System with Application to Near-Optimal Controller Design

Optimization and Control 2022-04-05 v1

Abstract

The negative imaginary (NI) systems theory has attracted interests due to the robustness properties of feedback interconnected NI systems. However, a full output optimal controller-synthesis methodology, for such class of systems, is yet to exist. In order to develop a solution towards this problem, we first develop a methodology to find the nearest NI system to a non NI system. This later problem stated as follows: for any linear time invariant (LTI) system defined by the state space matrices (A,B,C,D)(A, B, C, D), find the nearest NI system, with the state space matrices (A+ΔA,B+ΔB,C+ΔC,D+ΔD)(A+\Delta_A,B+\Delta_B,C+\Delta_C,D+\Delta_D), such that the norm of (ΔA,ΔB,ΔC,ΔD)(\Delta_A,\Delta_B,\Delta_C,\Delta_D) is minimized. Then, this methodology will be used to find the nearest optimal controller for a given NI plant. In other words, for a given NI system, an optimal control methodology, such as LQG, is used to design an optimal controller that satisfy a particular performance measure. Then, the developed methodology of finding the nearest NI system is used, as a near-optimal control synthesis methodology, to find the nearest NI system to the designed optimal controller. Hence, the synthesized controller satisfy the NI property and therefore guarantee a robust feedback loop with the negative imaginary system under control.

Keywords

Cite

@article{arxiv.2204.00952,
  title  = {Finding the Nearest Negative Imaginary System with Application to Near-Optimal Controller Design},
  author = {Mohamed Mabrok},
  journal= {arXiv preprint arXiv:2204.00952},
  year   = {2022}
}
R2 v1 2026-06-24T10:35:49.043Z