Petersen, I. R.2026-07-032026-07-0308582529960313-6922ORCID:/0000-0003-4856-9450/work/219177698https://hdl.handle.net/1885/733812634This paper presents a procedure for designing a reduced order observer and feedback control law to stabilize a given uncertain linear system. The uncertain systems are described by state equations containing unknown but bounded uncertain parameters. These parameters are allowed to be time-varying. The design procedure involves finding the solutions to two algebraic Riccati equations. The solutions to these Riccati equations are used to construct the required feedback gain and observer gain matrices. These solutions are used to form a quadratic Lyapunov function which is used to establish the stability of the closed loop system.5en19860022883762