Take a planet gear mechanism as an example. Static system is Oxy Moving system iS O1 Iry Relative motion: rotation about axis O2, y 0. is the relative angular velocity. Embroiling motion rotation about axis O1 @, is the embroiling angular velocity (Look for the animation on the next page) 77 （Look for the animation on the next page） Take a planet gear mechanism as an example. Static system is O1 xy Moving system is O1 x'y' Relative motion: rotation about axis O2 , r is the relative angular velocity. Embroiling motion: rotation about axis O1 , e is the embroiling angular velocity