Van der Pol oscillator


Van der Pol oscillator

In dynamics, the Van der Pol oscillator (named for Dutch physicist Balthasar van der Pol) is a type of nonconservative oscillator with nonlinear damping. It evolves in time according to the second order differential equation:

:{d^2x over dt^2}+mu(x^2-1){dx over dt}+x= 0

where "x" is the position coordinate — which is a function of the time "t", and "μ" is a scalar parameter indicating the strength of the nonlinear damping. It can be proven via Liénard's Theorem that there exists a limit cycle for the undriven Van der Pol oscillator, thus making it an example of a Liénard system.

History

The van der Pol oscillator was originally “discovered” by the Dutch electrical engineer and physicist Balthasar van der Pol. Van der Pol found stable oscillations, now known as limit cycles, in electrical circuits employing vacuum tubes. When these circuits are driven near the limit cycle they become entrained, i.e. the driving signal pulls the current along with it. Van der Pol and his colleague van der Mark reported in the September 1927 issue of Nature van der Pol, B. and van der Mark, J., “Frequency demultiplication”, "Nature", 120, 363-364, (1927).] that at certain drive frequencies an irregular noise was heard. This irregular noise was always heard near the natural entrainment frequencies. This was one of the first discovered instances of deterministic chaos.

The van der Pol equation has a long history of being used in both the physical and biological sciences. For instance, in biology, FitzhughFitzhugh, R., “Impulses and physiological in theoretical models of nerve membranes”, "Biophysics J", 1, 445-466, (1961).] and NagumoNagumo, J., S. Arimoto, and S. Yoshizawa, "An active pulse transmission line simulating nerve axon", "Proc IRE", 50, 2061-2070, (1962).] extended the equation in a planar field as a model for action potentials of neurons. The equation has also been utilised in seismology to model the two plates in a geological fault.

Results

*When "μ" < 0, the system will be damped.

*When "μ" = 0, i.e. there is no damping function, the equation becomes:

:{d^2x over dt^2}+x= 0

:This is a form of the simple harmonic oscillator. Therefore, "x" is always varying with "t" at a proportional rate to {dx over dt}, the velocity, i.e. the distance of the pendulum, say, from the zero point, is proportional to its velocity from that same point. Due to this energy is conserved and there is no work done.

*When "μ" ≥ 0, the system will enter a limit cycle, where energy continues to be conserved. Energy can still be lost and work done if the system does not enter a limit cycle immediately.

*When |"μ"| >> 0, the system is heavily damped and loses all energy extremely quickly.

The Forced Van der Pol oscillator

The forced, or driven, van der Pol oscillator takes the 'original' function and adds a driving function "A"sin("ωt") to give a differential equation of the form:

:{d^2x over dt^2}-mu(1-x^2){dx over dt}+x-A sin(omega t)= 0

where "A" is the amplitude, or displacement of the wave function and "ω" is its angular velocity.

References

External links

* [http://scholarpedia.org/article/Van_der_Pol_oscillator Van der Pol oscillator on Scholarpedia]
* [http://www.cmp.caltech.edu/~mcc/Chaos_Course/Lesson3/Demos.html Van Der Pol Oscillator Interactive Demonstrations]


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Van-der-Pol-Oszillator — Der Van der Pol Oszillator ist ein schwingungsfähiges System mit nichtlinearer Dämpfung und Selbsterregung. Für kleine Amplituden ist die Dämpfung negativ (die Amplitude wird vergrößert). Ab einem bestimmten Schwellwert der Amplitude wird die… …   Deutsch Wikipedia

  • Van-der-Pol-System — Der Van der Pol Oszillator ist ein schwingungsfähiges System mit nichtlinearer Dämpfung und Selbsterregung. Für kleine Amplituden ist die Dämpfung negativ (die Amplitude wird vergrößert). Ab einem bestimmten Schwellwert der Amplitude wird die… …   Deutsch Wikipedia

  • Oscilador de van der Pol — Plano de fases de un oscilador de van der Pol no forzado. Evolución del ciclo …   Wikipedia Español

  • Balthasar van der Pol — Infobox Scientist name = Balthasar van der Pol caption = birth date = birth date|1889|1|27 birth place = death date = death date and age|1959|10|6|1889|1|27 death place = residence = nationality = Dutch field = Physics work institution = alma… …   Wikipedia

  • Chaos theory — This article is about chaos theory in Mathematics. For other uses of Chaos theory, see Chaos Theory (disambiguation). For other uses of Chaos, see Chaos (disambiguation). A plot of the Lorenz attractor for values r = 28, σ = 10, b = 8/3 …   Wikipedia

  • PROPT — Infobox Software name = PROPT developer = [http://tomopt.com/ Tomlab Optimization Inc.] latest release version = 6.1 latest release date = release date|2008|06|11 operating system = [http://tomopt.com/tomlab/about/ TOMLAB® OS Support] genre =… …   Wikipedia

  • Delft University of Technology — Technische Universiteit Delft Motto Challenge the Future …   Wikipedia

  • Предельный цикл — В теории динамических систем и дифференциальных уравнений, предельным циклом векторного поля на плоскости или, более обобщённо, на каком либо двумерном многообразии называется замкнутая (периодическая) траектория этого векторного поля, в… …   Википедия

  • FitzHugh–Nagumo model — The FitzHugh Nagumo model (named after Richard FitzHugh, 1922 ndash;2007) describes a prototype of an excitable system, i.e., a neuron.If the external stimulus I { m ext} exceeds a certain threshold value, the system will exhibit a characteristic …   Wikipedia

  • List of mathematics articles (V) — NOTOC Vac Vacuous truth Vague topology Valence of average numbers Valentin Vornicu Validity (statistics) Valuation (algebra) Valuation (logic) Valuation (mathematics) Valuation (measure theory) Valuation of options Valuation ring Valuative… …   Wikipedia


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.