链轮驱动系统的多刚体建模及分析

采用多刚体方法对链条链轮系统的驱动过程进行了建模和动力学分析．链节看作刚体，链轮看作等边刚性多边形，辊子看作两个链节之间的旋转副．啮合约束当作可变约束处理，当啮合力为正时，链节和链轮之间是固定约束，当力变负时，链节脱离链轮．利用龙格库塔法求解系统的拉格朗日方程．最后计算并分析了不同工况下的驱动过程，解释了系统的锁死现象，并进一步分析了两种避免锁死的处理方法．

MODELING AND SIMULATION OF THE CHAIN-SPROCKET SYSTEM WITH MULTI RIGID BODY METHOD

This paper deals with the driving process of chain sprocket system with the multi rigid body dynamics method. With the model, the process of the dynamical response is analyzed. The link is treated as a rigid bar, the sprocket as a rigid polygon, and the roller between any two links as a revolving joint. The system is a closed kinematic chain of rigid bodies connected by revolving joints. The gear constraint is treated as a variable constraint. When the link meshes with the sprocket, the constraint force between the link and the sprocket is determined by testing. If the force is positive, the constraint is treated as a fixed constraint, otherwise the link leaves the sprocket. Lagrange's equation of motion is solved with Runge-Kutta method. Different driving processes are simulated and analyzed. The phenomenon of locking is explained, and two treatments to avoid locking of the system are proposed and analyzed.