Stability boundary determination for unity feedback systems with transport delay and flexible loop gain

Consider the stability equation method applied for some systems with nonlinearities. Up to the present, there was no explicit formula which can define the stable region on the parameter space. This paper proposes a systematic computation structure for determining the stability boundary of stable regions on the parameter plane applied to unity feedback systems with transport delay and flexible loop gain. A set of stability boundary equations is carefully defined and a theorem for computation is given. Solutions for these equations describe the stability boundary of the feedback system. Therefore, the permissible region of stable adjustable loop gain and transport delay can be successfully determined.