Abstract: After observation and experiment on nature snakes’ movement, snake’s ability of concertina motion in vertical pla-ne is discovered. Concertina motion of snake is widely adop-ted, especially in utmost hazardous environment. The principle, characteristics and the unique environments of both horizontal concertina motion and vertical concertina motion had been dis-cussed in detail subsequently. Kinematics mathematic models of these concertina motions are proposed and analyzed. The homologous bionic physical structure is designed in accordance with snakes’ concertina motion principle. Finally, according to mathematical models, experiment on the snake-like robot veri-fied the validity of these two gaits.

Key words: Bionics Modeling, Concertina motion, Snake-like robot