MESA LAB

ICFDA’14 Paper Review(On selected two papers)

Zhuo LiMESA (Mechatronics, Embedded Systems and Automation)LAB

School of Engineering,University of California, Merced

E: zli32@ucmerced.eduLab: CAS Eng 820 (T: 209-228-4398)

Jun 30, 2014. Monday 4:00-6:00 PMApplied Fractional Calculus Workshop Series @ MESA Lab @ UCMerced

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Interesting titles • Fractional order controller design for a large class of process models

• Vicente Feliu-Batlle, Raul Rivas-Perez, Fernando J. Castillo-Garcia, “Robust fractional-order temperature control of a steel slab reheating furnace with large time delay uncertainty”

• Robust Factional Order PID Controllers: The First Generation CRONE CSD Approach

• Victor Kubyshkin and Sergey Postnov, “Optimal Control Problem for Linear Fractional-Order Systems”

• Gain and Order Scheduled Fractional-order PID Control Of Fluid Level in a Multi-Tank System

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AFC Workshop Series @ MESALAB @ UCMerced04/21/2014

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Paper I

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Paper I

• Reasons why it is interesting– I’ve seen many papers on FO PID that don’t succeed

in originality. Most apply/implement the “flat phase” tuning rule for FO PID design.• Fractional order – Igor Podlubny• “Flat phase” tuning rules – Yangquan Chen

– This paper proposed something new by combining other specification

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Argument

• “All controller design methods deals with particular forms of the process model. The controller tuning algorithms are presented using the studied particular plant. In the present work the authors propose the fractional order and controller design algorithms in general form, using any type of process model.”

• , a general FO transfer function

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General design specifications 1. Phase margin and gain crossover frequency specifications:

2. Robustness to variations in the gain of the plant.

3. High-frequency noise rejection.

4. Good output disturbance rejection.

5. Steady-state error cancellation.

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My doubt

• Two case studies

• Wcg = 10rad, ph = 60

• Wcg = 100rad, ph = 60

• Is it guaranteed to give solution?• What if the process has delay.

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Paper II

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Paper II• Reasons why it is interesting to me

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Let’s read its conclusion“This paper presented the Control System Design of controller using the frequency-domain approach. He focuses on PID, fractional order PID and then on first generation CRONE controllers. Fractional order controllers provide more tuning parameters that are used for the robustness purpose by the CRONE methodology. First generation CRONE controllers can be used for plants with magnitude uncertainty and constant phase. When the plant phase varies with respect to the frequency, the second CRONE generation design can be used. It proposes a required nominal open-loop transfer function defined from that of a fractional order integrator. Complex fractional orders have been used to develop the CRONE approach [19, 20, 21, 5] and other approaches [2]. The third CRONE generation design has been developed for plants with both gain and phase uncertainties. Today, the CRONE CSD permits to tackle non-minimum phase, time delay, unstable or undamped plants [5, 7, 21] and linear time varying plants [29]. It has been extended for the control of MIMO plants [6, 16].”

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Academic parallel

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Serial

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The first generation CRONE methodology • To use a controller without phase variation around frequency Wcg. This strategy

has to be used when frequency Wcg is within a frequency range where the plant phase is constant. In this range where the plant frequency response is asymptotic the plant perturbation is only gain like. The CRONE controller is defined within a frequency range [WA, WB] around the desired frequency Wcg from the fractional transfer function of an order n integro-differentiator:

• with n and C0R

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Summary

• To sum up, this CRONE controller is robust even if it requires a greater control level and more time to reject an input disturbance. It illustrates perfectly the robustness/performance trade-off.

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