Abstract: Though scissors-like atomic units can construct a planar mechanism with pantograph characteristics, it needs at least two inter-connected atomic spatial mechanisms. In order to overcome the weakness, a novel planar structure, which is constructed by rigid links and compliant joints without intercrossed connection, is proposed. The principle of the mechanism is to construct a parallelogram four-bar linkage with pantograph characteristics by using the bar midpoints of a random four-bar mechanism. Further this principle is applied to a random-bar mechanism to achieve its pantograph characteristics by dividing it into triangles and quadrangles. The proposed method presents a general solution to the design of pantograph-like random-bar mechanisms In addition, this mechanism can be used in the balance for inertia force of mechanisms.

Key words: Balance of inertia force, Combination, Parallelogram mechanisms, Planar pantograph