Real-time tension estimation in the spinning process based on the natural frequencies extraction of the Polyester Filament Yarn

•The theoretical relationship is established among the PFY tension, the spinning speed, and the first natural frequency in the spinning process.•The improved wavelet threshold denoising model has been applied to denoising the vibration signals, and the gravity center frequency of the denoised amplitude spectrum is used to extract the natural frequency of the PFY.•A new real-time evaluation index is proposed to evaluate the overall tension fluctuation of the PFY in the spinning process.