On Smith predictor based controllers for plants with time delay and multiple unstable modes

This work proposes an extension of the Smith predictor to design stabilizing controllers for linear time-invariant (LTI) time-delay single-input single-output (SISO) systems with multiple unstable modes. The main contribution of this method is that it simplifies earlier predictor-based control designs for unstable plants. The predictor filters are designed by solving a Nevanlinna–Pick interpolation problem for optimal robust stability.