The necessary and sufficient conditions for the input angle to be rotatable angle of N-bar linkages and the rotatability of five-bar are firstly proved according to the theory of N-bar linkages.

• 首先根据N杆机构的理论，得到了五杆机构的分类以及五杆机构中两相邻杆的夹角为周转角时的充分必要条件以及五杆机构能够整周转动时的充分必要条件。