Fractional-order control

Fractional-order control (FOC) is a field of control theory that uses the fractional-order integrator as part of the control system design toolkit. The use of fractional calculus can improve and generalize well-established control methods and strategies.^[1]

The fundamental advantage of FOC is that the fractional-order integrator weights history using a function that decays with a power-law tail. The effect is that the effects of all time are computed for each iteration of the control algorithm. This creates a "distribution of time constants", the upshot of which is there is no particular time constant, or resonance frequency, for the system.

In fact, the fractional integral operator ${\displaystyle {\frac {1}{s^{\lambda }}}}$ is different from any integer-order rational transfer function ${\displaystyle {G_{I}}(s)}$, in the sense that it is a non-local operator that possesses an infinite memory and takes into account the whole history of its input signal.^[2]

Fractional-order control shows promise in many controlled environments that suffer from the classical problems of overshoot and resonance, as well as time diffuse applications such as thermal dissipation and chemical mixing. Fractional-order control has also been demonstrated to be capable of suppressing chaotic behaviors in mathematical models of, for example, muscular blood vessels^[3] and robotics.^[4]

Initiated from the 1980's by the Pr. Oustaloup's group, the CRONE approach^{[clarification needed]} is one of the most developed control-system design methodologies that uses fractional-order operator properties.^{[citation needed]}

See also

• Differintegral
• Fractional calculus
• Fractional-order system

External links

• Dr. YangQuan Chen's latest homepage for the applied fractional calculus (AFC)
• Dr. YangQuan Chen's page about fractional calculus on Google Sites

References

1. Monje, C.A., Chen, Y., Vinagre, B.M., Xue, D. and Feliu-Batlle, V., 2010. Fractional-order systems and controls: fundamentals and applications. Springer Science & Business Media.https://www.springer.com/gp/book/9781849963343
2. Tavazoei, M.S.; Haeri, M.; Bolouki, S.; Siami, M. (2008). "Stability preservation analysis for frequency-based methods in numerical simulation of fractional-order systems". SIAM Journal on Numerical Analysis. 47: 321–338. doi:10.1137/080715949.
3. Aghababa, Mohammad Pourmahmood; Borjkhani, Mehdi (2014). "Chaotic fractional-order model for muscular blood vessel and its control via fractional control scheme". Complexity. 20 (2): 37–46. Bibcode:2014Cmplx..20b..37A. doi:10.1002/cplx.21502.
4. Bingi, Kishore; Rajanarayan Prusty, B.; Pal Singh, Abhaya (2023-01-10). "A Review on Fractional-Order Modelling and Control of Robotic Manipulators". Fractal and Fractional. 7 (1): 77. doi:10.3390/fractalfract7010077. ISSN 2504-3110.