Koopman-based synchronization analysis and residual diagnostics of coupled Van der Pol oscillators
摘要
Synchronization in coupled nonlinear oscillators is central to understanding collective behavior in physics, biology, and engineering. This work presents a Koopman operator-based framework for analyzing synchronization in diffusively coupled Van der Pol oscillators, with a brief extension to a bio-inspired fish robot model. Traditional time-domain and Hilbert-phase analyses identify phase coherence for sufficiently strong coupling, but the Koopman approach provides a richer operator-theoretic view by lifting nonlinear dynamics into a linear observable space. Extended Dynamic Mode Decomposition (EDMD) is employed to compute Koopman spectra and modes, revealing oscillatory stability and latent synchronization manifolds. Data-driven embeddings using Principal Component Analysis (PCA), t-distributed stochastic neighbor embedding (t-SNE), and K-means uncover coherent structures and phase-locking regimes. Further, residual diagnostics quantify model fidelity and allow estimation of coupling strength. Results demonstrate robust synchronization across small oscillator networks and confirm scalability up to