Tokay geckos are skillful climbers and are able to negotiate difficult terrain such as steep slopes and overhanging inclines without losing their foothold. Here,we present data on the changes in locomotor kinematics when geckos are challenged to walk on various inclined surfaces. We trained individual geckos to move along a platform which can be tilted to simulate different slopes.The animals were filmed using a high-speed video camera.The results showed that their speed decreased with increasing slope angle, and their speed on the steep and inverted slopes(sloped angle >60°) decreased at a faster rate than on the shallow slopes(sloped angle<60°). The geckos' stride length was much greater on the shallow slopes compared to the inverted slopes. The influence of stride length and stride frequency on speed was different when the geckos moved across different slopes. There are significant differences duty factor, which varied from 0.54 when wall climbing(90° slope) to 0.84 when walking on the ceiling(180° slope). The mechanisms revealed this study will improve our understanding of control strategies in kinematics and inspire the design of robots with greater mobility.
Zhou-Yi WangAi-Hong JiThomas EndleinWei LiDiana SamuelZhen-Dong Dai
The study of the adhesion of millions of setae on the toes of geckos has been advanced in recent years with the emergence of new technology and measurement methods. The theory of the mechanism of adhesion by van der Waals forces is now accepted and broadly understood. However, this paper presents limitations of this theory and gives a new hypothesis of the biomechanism of gecko adhesion. The findings are obtained through measurements of the magnitude of the adhesion of setae under three different conditions, to show the close relationship between adhesion and status of the setae. They are reinforced by demonstrating two setal structures, follicle cells and hair, the former making the setae capable of producing bioelectrical charges, which play an important role in attachment and detachment processes. It is shown that the abundant muscular tissues at the base of the setae cells, which are controlled by peripheral nerves, are instrumental in producing the foot movement involved in attachment and detachment. Our study will further uncover the adhesion mechanism of geckos, and provide new ideas for designing and fabricating synthetic setae.
