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VSC is another name for sliding mode control. It should be a redirect. It should not be deleted. |
Made VSC a real article (rather than a redir to sliding mode). |
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[[Variable structure control]], or '''VSC''', is form of [[Classification of discontinuities|discontinuous]] [[nonlinear control]]. The method alters the [[dynamic system|dynamics]] of a [[nonlinear system]] by application of a high-frequency ''switching control''. The [[state space (controls)|state]]-[[feedback]] control law is ''not'' a [[continuous function]] of time; it ''switches'' from one smooth condition to another. So the ''structure'' of the control law ''varies'' based on the position of the state trajectory; the method switches from one smooth control law to another and possibly very fast speeds (e.g., for a [[countably infinite]] number of times in a finite time interval).
Presently, the main mode of VSC operation is [[sliding mode control]] (SMC). The strengths of SMC include:
* Low sensitivity to [[plant (control theory)|plant]] parameter uncertainty
* Greatly reduced-order modeling of plant dynamics
* Finite-time convergence (due to discontinuous control law)
The weaknesses of SMC include:
* [[Chatter]]ing due to implementation imperfections
* Over-focus on ''matched'' uncertainties (i.e., uncertainties that enter into the control channel)
However, the evolution of VSC is presently an active area of research.<ref name="EFF06">{{citation|title=Advances in Variable Structure and Sliding Mode Control|editor1-last=Edwards|editor1-first=Cristopher|editor2-last=Fossas Colet|editor2-first=Enric|editor3-last=Fridman|editor3-first=Leonid|publisher=Springer-Verlag|___location=Berlin|date=2006|series=Lecture Notes in Control and Information Sciences|volume=vol 334|isbn=978-3-540-32800-1}}</ref>
== See also ==
*[[Nonlinear control]]
*[[Robust control]]
*[[Optimal control]]
*[[H-bridge]] — A topology that combines four switches forming the four legs of an "H". Can be used to drive a motor (or other electrical device) forward or backward when only a single supply is available. Often used in actuator in sliding-mode controlled systems.
*[[Switching amplifier]] — Uses switching-mode control to drive continuous outputs
*[[Delta-sigma modulation]] — Another (feedback) method of encoding a continuous range of values in a signal that rapidly switches between two states (i.e., a kind of specialized sliding-mode control)
*[[Pulse density modulation]] — A generalized form of delta-sigma modulation.
*[[Pulse-width modulation]] — Another modulation scheme that produces continuous motion through discontinuous switching.
== Further reading ==
{{refbegin}}
*{{cite book
| last = Khalil
| first = H.K.
| authorlink = Hassan K. Khalil
| year = 2002
| edition = 3<sup>rd</sup> edition
| url = http://www.egr.msu.edu/~khalil/NonlinearSystems/
| isbn = 0-13-067389-7
| title = Nonlinear Systems
| publisher = [[Prentice Hall]]
| ___location = Upper Saddle River, NJ}}
*{{cite book
| author = [http://www.ece.osu.edu/~utkin/ Utkin, V.I.]
| title = Sliding Modes in Control and Optimization
| publisher = Springer-Verlag
| date = 1992
| pages =
| isbn = 978-0387535166
}}
*{{cite book
| editor-last = Zinober
| editor-first = A.S.I.
| editorlink = Alan S.I. Zinober
| title = Deterministic control of uncertain systems
| publisher = Peter Peregrinus Press
| place = London
| date = 1990
| isbn = 978-0863411700
}}
*{{cite book
| editor-last = Zinober
| editor-first = Alan S.I.
| title = Variable Structure and Lyapunov Control
| publisher = Springer-Verlag
| place = London
| date = 1994
| isbn = 978-3-540-19869-7
| doi = 10.1007/BFb0033675
}}
{{refend}}
== References ==
{{reflist}}
{{tech-stub}}
[[Category:Nonlinear control]]
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