First, the full name of multibody dynamics is "multibody system dynamics". It is a science that studies the motion law of multi-body systems (usually composed of several interconnected flexible and rigid objects). Multi-body system dynamics includes multi-rigid body system dynamics and multi-flexible body system dynamics. 2. The main tasks of multibody dynamics are: 1. The mathematical model of kinematics and dynamics of complex mechanical system is established, and the software system is developed to realize this mathematical model. Users only need to input the most basic data describing the system, and they can automatically carry out programmed processing with the help of a computer; 2. Develop and implement effective computer methods and numerical integration methods to deal with mathematical models, and automatically obtain kinematic laws and dynamic responses; 3. Realize effective data post-processing and provide data processing results in animation, charts or other ways. At present, multi-body dynamics has formed a relatively systematic research method. Among them, there are mainly analytical mechanics methods represented by Lagrange equation, vector science methods represented by Newton-Euler equation, graph theory methods commonly used in engineering, Kane method, variational method and so on.