For forward singularity, the Jacobins matrix is obtained based on velocity projection, a new notion of spatial instantaneous axis is introduced, and the expressive form of the parallel mechanism singularity is given when it is generated.

• 对于正奇异，推导出一种基于速度投影的雅可比矩阵求解方法，提出了空间瞬时轴这一新的概念，并给出奇异产生时并联机构正奇异的表现形式。