Performance comparison and robustness studies of robust bode and IMC based controllers for plants with large time delay

Controller design of a plant having large time delay using two different methods viz., Internal Model Control (IMC) and a controller based on the Robust Bode (RBode) method are reported. In particular, a boiler burning process is considered as plant which can be modeled as a First Order Plus Delay Time (FOPDT) system, where the time delay is fairly large and comparable to the plant time constant. Performance comparison and robustness studies are done considering nominal as well as off-nominal (using structured uncertainties) cases. Extension of the methods for higher order systems is conjectured.