1. Robustness Improvement of the Fractional-Order LADRC Scheme for Integer High-Order System
- Author
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Khalid Munawar, Ubaid M. Al-Saggaf, Ibrahim Mustafa Mehedi, Rachid Mansouri, and Maamar Bettayeb
- Subjects
Computer science ,020208 electrical & electronic engineering ,02 engineering and technology ,Active disturbance rejection control ,Transfer function ,Step response ,Control and Systems Engineering ,Robustness (computer science) ,Control theory ,Cascade ,Integrator ,0202 electrical engineering, electronic engineering, information engineering ,State observer ,Electrical and Electronic Engineering ,Design methods - Abstract
This article deals with a novel fractional-order active disturbance rejection control (FADRC) scheme to handle a general integer-order system. The proposed control structure enhances the robustness and performance of the classical active disturbance rejection control, especially for the open-loop gain variation. Based on the Bode's ideal transfer function, an analytical design of a state-feedback control is proposed. The integer-order model of the system to be controlled is first transformed to a noninteger-order one, where the introduced fractional order is a design parameter, which imposes the overshoot of the closed-loop step response. In addition, because the model of the system is transformed to a cascade of integer- and fractional-order integrator (the model is noncommensurate), a commensurate fractional-order extended state observer is proposed to estimate the generalized disturbance. To improve the robustness of the proposed FADRC scheme, an analytical design method of a noncommensurate state-feedback control is proposed. The proposed design method is based on the Bode's ideal transfer function cascaded with an integer-order filter. The proposed FADRC scheme is applied for a pendulum–cart test bed, and the effectiveness and robustness of the proposed control are examined by experiments.
- Published
- 2021