Predictive Generalized Active Disturbance Rejection Control for Fractional Order Systems With Time Delay

Abstract

In this paper, two different active disturbance rejection control techniques based on notion of Smith Predictor are proposed for control of fractional order stable systems with time delay. In the proposed Smith Predictor-based fractional order linearized active disturbance rejection control (SP-FO-LADRC) technique, fractional order dynamics are treated as a part of generalized disturbance, and the concept of Smith Predictor is used to obtain delay less output, which is fed to an extended state observer (ESO), and an integer order control strategy is developed. To further ameliorate control performance of this technique, complete plant information of commensurate fractional order system is used to formulate another new technique, namely, Smith Predictor-based fractional order generalized active disturbance rejection control (SP-FO-GADRC), which incorporates fractional ESO and leads to formulation of fractional order control law. An extensive simulation study and robustness analysis conducted on three different examples is testimony to efficacy of proposed techniques.