Contact force identification in pantograph–catenary system via elastic support beam theory and enhanced l1 sparse regularization scheme

Accurate identification of pantograph–catenary contact force remains a challenging inverse problem, particularly under high-speed operating conditions where high-frequency dynamics play a critical role. Most existing contact force identification methods are primarily limited to low-frequency ranges (typically below 20 Hz), which restricts their applicability in analyzing high-frequency phenomena such as contact strip abnormal wear and fatigue crack initiation in pantograph structures. To overcome these limitations, this study proposes a contact force identification framework with extended frequency capability for pantograph–catenary systems. Based on an elastically supported beam representation of the pantograph head with moving supports, this study establishes consistent forward and inverse dynamic models within a modal superposition framework, enabling an improved description of structural flexibility and high-frequency dynamic characteristics. Furthermore, an enhanced sparse inversion scheme is developed by incorporating a redundant cascaded dictionary with moving-average L1 regularization, which effectively improves robustness against noise and enhances the extraction of transient and high-frequency force components. Numerical simulations under various operating conditions demonstrate that the proposed method achieves accurate and stable reconstruction of contact forces over a significantly extended frequency range, outperforming conventional inversion approaches. The proposed framework provides a reliable and high-resolution tool for dynamic analysis of pantograph–catenary interactions and offers promising potential for future real-time monitoring applications.