Robust Stability Analysis of Time Delay Control Systems

This contribution considers the application of the recently proposed technique for analyzing the robust stability of plants having a rational transfer function with independent parametric uncertainty structure controlled by a first order controller, known as the sixteen plant theory (SPT), to time delay systems.The case study is a heat exchanger represented by a first order plus time delay (FOPTD) model controlled by a proportional-integral (PI) controller.It has been demonstrated that the SPT is a very useful tool for analyzing the robust stability of single input single output (SISO) time delay systems which are commonly found in chemical process control problems.The SPT has also been used to compare the robustness of three popular controller tuning methods which clearly demonstrate its versatility.The computational effort required by the SPT can be significantly reduced by using symbolic computation.