Grazing-sliding bifurcations in planar $\mathbb{Z}_2$-symmetric Filippov systems
Xingwu Chen, Zhihao Fang, Tao Li
TL;DR
The paper analyzes grazing-sliding bifurcations in planar Filippov systems endowed with $\mathbb{Z}_2$-symmetry, focusing on a hyperbolic limit cycle that grazes the discontinuity at a fold to form a symmetric figure-eight. By employing differential-geometry tools and an explicit two-parameter unfolding, it proves that the grazing-sliding bifurcation set forms a codimension-two submanifold and derives a nondegeneracy condition that yields a complete, asymptotically described bifurcation diagram via a displacement-map approach. The authors construct a rigorous local framework using two preliminary lemmas, then determine, through a sequence of lemmas and a detailed expansion of transition maps, how nine distinct dynamical regimes arise and transition as parameters vary. The results are validated with an example that demonstrates the codimension-two unfolding in a concrete $\mathbb{Z}_2$-symmetric Filippov system, highlighting the practical relevance of the diagrammatic scenarios for sliding, grazing, and crossing cycles.
Abstract
This paper aims to explore the effect of $\mathbb{Z}_2$-symmetry on grazing-sliding bifurcations in planar Filippov systems. We consider the scenario where the unperturbed system is $\mathbb{Z}_2$-symmetric and its subsystem exhibits a hyperbolic limit cycle grazing the discontinuity boundary at a fold. Employing differential manifold theory, we reveal the intrinsic quantities of unfolding all bifurcations and rigorously demonstrate the emergence of a codimension-two bifurcation under generic $\mathbb{Z}_2$-symmetric perturbations within the Filippov framework. After deriving an explicit non-degenerate condition with respect to parameters, we systematically establish the complete bifurcation diagram with exact asymptotics for all bifurcation boundaries by displacement map method combined with asymptotic analysis.
