Fractional order robust control based on Bode's ideal transfer function

2008 ◽  
Vol 42 (6-8) ◽  
pp. 999-1014 ◽  
Author(s):  
Abdelbaki Djouambi ◽  
Abdelfatah Charef ◽  
Alina Voda-Besancon
Keyword(s):  
Robust Control ◽  
Transfer Function ◽  
Fractional Order ◽  
Bode’S Ideal Transfer Function

scholarly journals Robust Fractional Order PI Controller Tuning Based on Bode’s Ideal Transfer Function

2016 ◽  
Vol 49 (9) ◽  
pp. 158-163 ◽  
Author(s):  
Roohallah Azarmi ◽  
Mahsan Tavakoli-Kakhki ◽  
Ali Khaki Sedigh ◽  
Alireza Fatehi
Keyword(s):  
Transfer Function ◽  
Fractional Order ◽  
Pi Controller ◽  
Controller Tuning ◽  
Bode’S Ideal Transfer Function ◽  
Fractional Order Pi Controller

Predictor-based fractional disturbance rejection control for LTI fractional-order systems with input delay

2020 ◽  
Vol 42 (16) ◽  
pp. 3303-3319
Author(s):  
Sajad Pourali ◽  
Hamed Mojallali
Keyword(s):  
Transfer Function ◽  
Fractional Order ◽  
Disturbance Rejection ◽  
Closed Loop ◽  
Reference Model ◽  
Open Loop ◽  
Input Delay ◽  
Fractional Order Systems ◽  
Disturbance Rejection Control ◽  
Bode’S Ideal Transfer Function

In this paper, a predictor-based fractional disturbance rejection control (PFDRC) scheme is proposed for processes subject to input delay. The proposed scheme can be generally applied to open-loop stable, integrative, and unstable integer-order processes, but it can be particularly utilized for open-loop stable fractional-order systems. A closed-loop reference model is formulated based on Bode’s ideal transfer function. The primary control design objective is to enable the output of input-delay process to follow the closed-loop reference model. Towards this end, the closed-loop transfer function of the PFDRC must take the same structure as that of the reference model. Meanwhile, the adverse effects of the input delay must be mitigated. To meet the latter, a filtered Smith predictor (FSP) is employed to provide a prediction of delay-less output response. To address the former, process dynamics are treated as a common disturbance; then, a fractional-order extended state observer (FESO) is introduced to estimate the delay-less output response and also the total disturbance (i.e. external disturbance and system uncertainties). The PFDRC feedback controller is easily derived by the gain crossover frequency of Bode’s ideal transfer function which facilitates the tuning process. The convergence analysis of the FESO is carried out in terms of BIBO stability. The effectiveness of the proposed control scheme is verified through three illustrative examples from the literature.

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