Mechanism analysis of ancient Chinese crossbows

In ancient China, people integrated the original bow, the bowstring, and a cam mechanism to develop a powerful weapon which was named the crossbow. It was one of the most frequently used weapons during the 5th century BC to the 18th century AD. Because it used the elasticity of the bow and the bowstring to shoot arrows, it was used for long-distance attacks. After the 4th century BC, the technology of producing crossbows was very sophisticated. Since the topological structure of the crossbow has a different configuration during the shooting process, it is defined as a reconfigurable mechanism. This paper uses the topological matrix to present the topological structures of the original crossbow and the Chu State repeating crossbow. A brief history of the development of the crossbow in ancient China is given. The Mongolian traditional bow is provided as an example to describe the manufacturing process of the bow. Then, topological structures of the original crossbow and Chu State repeating crossbow are derived. The degrees of freedom of two crossbows are proposed to check the constrained motion. Finally, 3D computer graphics of two crossbows are presented to illustrate the shooting processes.