Smith Predictor Controller Design Using the Direct Synthesis Method for Unstable Second-Order and Time-Delay Systems

Industrial processes often involve a long time delay, which adversely affects the stability of closed-loop control systems. The traditional Smith Predictor (SP) is model-based controller used in with large delays. variation system parameters and load disturbance situations are disadvantages SP, researchers have, therefore, proposed modified SP structures. In this paper, design method based on direct synthesis approach structure discussed. design, an I-PD set-point tracking side cascading PD lead–lag rejection side. contrast other studies literature, use simpler controllers enables mathematical expressions that arise to be significantly reduced. examined under input effects for normal parameter-changing conditions models unstable second-order plus time-delay processes. first plant model has two poles, second one stable pole, third zero pole. When results obtained using were compared methods, significant improvements achieved terms tracking, rejection, robustness conditions.