Four Motion Branches of an Origami Based Eight Bar Spatial Mechanism

An eight bar spatial mechanism inspired from an origami paper fold by considering the carton panels as links and creases as revolute joints is proposed. The constraint deposition and motion characteristics analyses of the eight bar spatial mechanism show that the mechanism implements one screw motion and one pure translation. The configuration space of the mechanism comprises four subspaces. Through adding different geometrical constraints to the eight bar spatial mechanism, different motions of the end-effector are limited leading to three 2-DOF and one 1-DOF motion branches. Additional geometrical constrained conditions in four motion branches with aimed motions of double translations, single translation and two single screw motions are revealed. In the first two motion branches, the eight bar spatial mechanism remains the constant relative orientations of joint-axes. However, the joint-axes of the eight bar spatial mechanism change their orientations in the last two motion branches. Kinematic analyses are discussed in four motion branches, respectively.