The precise detection of polyester filament yarn (PFY) tension in the spinning process is critical to ensure product quality. The laser Doppler vibrometer (LDV) method is proposed to achieve non-contact detection of PFY tension in this paper. By employing the Hamilton principle, the transverse dynamics differential equations of PFY are derived, which are discretized and solved by the Galerkin method and Runge–Kutta method, respectively. In the equations, the PFY between two adjacent rollers is simplified as an axially moving string to verify the generality of calculating natural frequencies. The calculated natural frequencies from the axially moving string model are compared with solved results from the transverse dynamics differential equations. It is shown that the approximation of natural frequencies can be obtained from the axially moving string model. This study attempts to establish an approximate generic model among the PFY tension, the spinning speed and the first natural frequency based on axially moving string model, from which the PFY tension can be calculated efficiently by employing the measured natural frequencies. The LDV method is used to measure the natural frequencies. A major advantage of the proposed method is to realize non-contact detection of PFY tension. The method is more useful under high-speed spinning conditions where contact tension detectors are not available. An experimental analysis is carried out to verify the effectiveness and accuracy of the proposed method. Therefore, it is believed that the non-contact detection of PFY tension in the spinning process by the LDV method is feasible.

纺纱过程中涤纶长丝（PFY）张力的精确检测对于确保产品质量至关重要。本文提出了激光多普勒测振仪(LDV)方法来实现PFY张力的非接触检测。利用哈密顿原理，推导出PFY的横向动力学微分方程，分别用Galerkin方法和Runge-Kutta方法对其进行离散和求解。式中，将相邻两滚子之间的PFY简化为轴向移动的弦，以验证计算固有频率的通用性。从轴向移动的弦模型计算的自然频率与从横向动力学微分方程得到的结果进行比较。结果表明，自然频率的近似值可以从轴向移动的弦模型中获得。本研究试图在轴向移动弦模型的基础上建立PFY张力、旋转速度和第一固有频率之间的近似通用模型，从中可以利用测量的固有频率有效地计算PFY张力。LDV 方法用于测量固有频率。该方法的一个主要优点是实现了 PFY 张力的非接触式检测。该方法在接触张力检测器不可用的高速纺丝条件下更有用。进行了实验分析以验证所提出方法的有效性和准确性。所以，