Gear transmission system is a complex system with multiple excitation factors coupling each other. Considering all the internal and external excitation factors of gear transmission system to establish an analysis model for research, it will lead to the dynamic system is too complex to analyze the influence rules of some factors on the system. Therefore, according to the actual analysis needs and different analysis emphasis, it is an important issue for every researcher to establish a simplified analysis model with certain accuracy and easy to solve.

In the past research, Li Runfang and others systematically introduced the formation mechanism of several common excitation factors and several common research methods, enumerated several commonly used models such as torsion model, bending torsion shaft model and bending torsion shaft pendulum, and considered the excitation factors such as error, time-varying meshing stiffness, external load torque fluctuation, clearance and so on Great reference value.

Scholars in this field have done a lot of research on various excitation factors that affect the vibration characteristics of gear transmission. Liu Geng and others systematically expounded the causes of vibration caused by tooth surface friction, and analyzed the development status, research trend and main problems existing in the research on the influence of tooth surface friction on the vibration characteristics of gear transmission. Considering the time-varying stiffness, backlash, friction and other excitation factors, Xiang Ling et al. Established a six degree of freedom dynamic model of gear, and analyzed the bifurcation characteristics of gear system under the change of speed and bearing stiffness.

Ren Wei et al. Calculated the time-varying support stiffness curve, and analyzed that the time-varying support stiffness increased the system vibration by about 5%, and the time-varying support stiffness could not be ignored. Zou Yujing et al. Established a dynamic model considering oil film stiffness, friction torque and other factors, analyzed the influence of oil film stiffness and friction on gear transmission vibration and the coupling relationship between them. In addition, many internal and external excitation factors such as gear mass eccentricity, load torque fluctuation and input speed fluctuation are considered.