Experimental study on morphology and kinematics of mudskipper in amphibious environments

Mudskippers exhibit the unusual feature of the fact that they not only can walk on land, but also uniquely adapt to intertidal habitats, their excellent amphibious performance inspire many researchers to develop amphibious biomimetic robots. In this paper, the morphological parameters of the mudskipper were measured Then, a simple and efficient high speed photography system was introduced to investigate the kinematics of live mudskipper. In order to explore the kinematics of the mudskipper in amphibious environment, gelatin was used as an analogue for mud on the basis of their similar mechanical properties. Then, the image sequence of the mudskipper in water, on gelatin and glass were concretely studied with the help of digital image process, respectively. The tracked body midline of the mudskipper in water and on gelatin are obtained, we demonstrate that the mudskipper uses both body and pectoral fins for locomotion in water and on gelatin simultaneously, while only uses pectoral fins for locomotion on land. The speed and the related angle of the mudskipper were also calculated, the speed in water is much faster than on gelatin. The displacement of the center of mass of the mudskipper on glass is also calculated. The performance of the mudskipper in different environments is very instructional and actual significance to mimic an amphibious robot.