Upper bound of the number of limit cycles for symmetric scalar piecewise linear differential equations with three zones

Fuente: arXiv
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Hauptverfasser: Bravo, J. L., Carmona, V., Fernández, M., Ojeda, I.
Format: Preprint
Veröffentlicht: 2025
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author Bravo, J. L.
Carmona, V.
Fernández, M.
Ojeda, I.
author_facet Bravo, J. L.
Carmona, V.
Fernández, M.
Ojeda, I.
contents The study of the dynamics of a continuous observable and non-controllable three-dimensional symmetric piecewise linear system with three zones can be reduced to the study of the existence of limit cycles for the piecewise differential equation $x'=ax+(b-a)\mathop{\rm sat}(x)+μ\sin t$, where $\operatorname{sat}$ stands for the normalized saturation function. This paper proves that the number of limit cycles of the equation is finite independently of $a,b,μ$. Moreover, it is proven that the maximum number of limit cycles is exactly one or three for certain values of the parameters. Using Melnikov theory for a certain deformation of the equation, it is proven that for small values of the perturbation parameter, there are exactly three, five or one limit cycles, depending on the values of $μ$. This strengthens the conjecture that the equation has at most five limit cycles.
format Preprint
id arxiv_https___arxiv_org_abs_2507_06705
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Upper bound of the number of limit cycles for symmetric scalar piecewise linear differential equations with three zones
Bravo, J. L.
Carmona, V.
Fernández, M.
Ojeda, I.
Dynamical Systems
Classical Analysis and ODEs
Primary 34C25. Secondary: 34A34, 37C27, 37G15
The study of the dynamics of a continuous observable and non-controllable three-dimensional symmetric piecewise linear system with three zones can be reduced to the study of the existence of limit cycles for the piecewise differential equation $x'=ax+(b-a)\mathop{\rm sat}(x)+μ\sin t$, where $\operatorname{sat}$ stands for the normalized saturation function. This paper proves that the number of limit cycles of the equation is finite independently of $a,b,μ$. Moreover, it is proven that the maximum number of limit cycles is exactly one or three for certain values of the parameters. Using Melnikov theory for a certain deformation of the equation, it is proven that for small values of the perturbation parameter, there are exactly three, five or one limit cycles, depending on the values of $μ$. This strengthens the conjecture that the equation has at most five limit cycles.
title Upper bound of the number of limit cycles for symmetric scalar piecewise linear differential equations with three zones
topic Dynamical Systems
Classical Analysis and ODEs
Primary 34C25. Secondary: 34A34, 37C27, 37G15
url https://arxiv.org/abs/2507.06705