Abstract: A complex amphibious robotic mechanism is designed on the basis of analysis of recent advances at home and abroad. The robot is based on the alligator and can both crawl and swim. After simulation and optimization on the complex alligator imitation mechanism, the ratio between body length and leg length for the robot to get optimum movement effect is obtained, i.e. 17:13. It is believed that when the waist turns to a certain angle, the movement performance becomes better and better with the increase of the ratio between leg length and body length, and when the waist turns to the limit torsion angle, it obeys the approximate parabola law. At last, a principle prototype is made. The results of creeping and swimming experiments show that the best frequency for the robot to get optimum movement effect is 2 Hz.

Key words: Amphibious biorobot, Complex mechanism, Principle prototype, Simulation