基于激光多普勒效应和转动动力学原理, 提出一种直接监测转轴动态扭矩的新方法, 并建立了数学模型。通过构造光学测试系统使4束高相干激光投射到转轴轴段两截面上4点, 具有多普勒频移的反射光在光电探测器上发生混频, 光电流频差正比于角速度。测得相邻时刻两截面的瞬时转速, 得到轴段转速波动值及两端面相对转速波动值, 进而实现转轴动态扭矩的直接监测。实验验证了该方法的可行性。与传统方法相比, 该方法实时性强, 具有较宽的动态范围, 对动态扭矩的识别值提高了5%～10%, 反映了转轴扭矩波动的动态特性。

Based on laser Doppler effect and principle of rotational dynamics, a novel approach to dynamic torque measurement is proposed. Mathematical model of measurement method is deduced. Four highly coherent laser beams irradiate four points of two sections of rotating shaft by designed optical measurement system. Backscattered lights with Doppler frequency shift are mixed onto the surface of photo-detectors, heterodyning takes place, and the output current is modulated. The photocurrent frequency difference is proportional to rotational velocity. Speed fluctuation values of rotating shaft segment and relative speed fluctuation values of between sections are obtained directly by measuring instantaneous rotational velocity of double sections in two successive times, and then dynamic torque values are obtained. Experimental results indicate that the identification values of dynamic torque are improved 5%～10%, which reflects the dynamic characteristic of torque fluctuation. Compared to conventional measurement approaches, this approach can promote the dynamic measurement range, and is more real-time.