Smith predictor embedded analytical fractional-order controller design: A delayed Bode’s ideal transfer function approach

Abstract

Abstract The main contribution of this paper is to design an enhanced fractional-order controller for the higher-order system. The analytical design methodology utilizes a delayed Bode’s ideal transfer function in place of the conventional one as the reference model. A reduced fractional-order plus dead-time transfer function is used to represent a higher-order process. The design also embeds a Smith predictor for the enhanced closed-loop performance. Analytical tuning for the designed fractional-order controller is provided based on frequency domain specifications. The proposed methodology is applied to two higher-order systems, which can be represented by a reduced fractional-order plus dead-time transfer function. The closed-loop performance of the designed controller is compared with that of the three other related controllers. Frequency domain characteristics, load disturbance, sensitivity analysis, and model mismatch performance are demonstrated and compared with those of other controllers as well. The results of the paper reveal that the proposed controller leads to an overall enhanced closed-loop performance.