2.1Basic Concepts of Mechanisms(4) Lower pairs(低副) joints with surface contact Prismatic joint Revolute joint Cylindric joint Spherical joint Helical joint Planar joint ype joint R joint C joint S ioint f joint DOFLower pairs（低副）:joints with surface contact Prismatic joint Revolute joint Cylindric joint Spherical joint Helical joint Planar joint Type P joint R joint C joint S joint H joint F joint DOF 1 1 2 3 1 3 2.1Basic Concepts of Mechanisms(4)