Chinese Science Bulletin © 2009 SCIENCE IN CHINA PRESS Citation: Guo C, Cai L, Xie H R, et al. Divisional and hierarchical innervations of G. gecko’s toes to motion and reception. Chinese Sci Bull, 2009, 54: 2880 2887, doi: 10.1007/s11434-009-0188-1 Divisional and hierarchical innervations of G. gecko’s toes to motion and reception GUO Ce 1† , CAI Lei 1 , XIE HeRui 1 , WANG ZhouYi 1 , DAI ZhenDong 1 & SUN JiuRong 2† 1 Institute of Bio-inspired Structure and Surface Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China; 2 College of Life Sciences, Peking University, Beijing 100871, China As a member of robot families, climbing robots have become one of the research hot-spots in the ro- botic field recently and Gekko gecko (G. gecko) has been broadly seen as an ideal model for climbing robot development. But for gecko-mimic robots, one of the key problems is how to design the robot’s foot. In this paper, (1) high-speed camera recording and electrophysiological method are used to ob- serve motion patterns of G. gecko’s foot when it climbs on different oriented surfaces; (2) nerve inner- vations of gecko’s toes to motion and reception are studied. It is found that the five toes of the G. gecko can be divided into two motion and reception divisions, and also its motion and reception are modu- lated and controlled hierarchically. The results provide important information and exclusive ideas for the foot design and control algorithm of gecko-mimic robots. Gekko gecko, nerve innervations, motion pattern, reception, robot foot The locomotion, sensing, navigation, and adaptation capabilities in animals have long inspired researchers in robotic system design. Recently, climbing robots have become one of hot spots in the robotic field due to its excellent capability to perform many tasks inaccessible to other robots or humans such as inspection, repair, cleaning, surveillance, and exploration. In the natural world, gecko’s climbing ability has attracted scientists’ attention since they can adhere to most surfaces robustly and climb with very high maneuverability and agility. But, for the gecko inspired robots, one of the key prob- lems is how to design the robot foot. In 2005, the re- searchers in Carnegie Mellon University developed a gecko inspired robot “Geckobot”, whose footpad was composed of 8 pieces of polydimethyl siloxane (PDMS) elastomer, and it could climb up to 85° stably on Plexi- glas surfaces [1] . Further, researchers in Stanford Univer- sity designed a gecko-mimic robot “Stickybot”, whose foot was similar to gecko’s, having 4 toes with sticky material, allowing it to adhere to or peel off the contact- ing surface, and it could climb on vertical glass surface freely [2] . We have already done lots of works in me- chanical design of gecko-robot’s foot and its motion control system [3–7] , now we are engaged in studying fine control and modulation of gecko’s toes motion and their reception properties. Gekko gecko (G. gecko) belongs to class reptilia, fam- ily Gekkonidae and is a typical 5 toed animal. Autumn and his colleagues provided the first direct experimental evidence for dry adhesion of gecko setae by Van der Waals forces [8,9] . Zaaf and his colleagues studied gait characteristics and the differences of muscle/skeletal systems between the ground-dweller Eublepharis macu- larius and the specialist climber G. gecko [10–12] . Autumn and Hsieh studied dynamics of geckos running verti- cally [13] . Li and Dai et al studied the joint angle changes of gecko’s forelimb and hindlimb when gecko walked or Received September 9, 2008; accepted February 9, 2009 doi: 10.1007/s11434-009-0188-1 † Corresponding authors (email: guozc@nuaa.edu.cn; sjr@pku.edu.cn) Supported by the National Natural Science Foundation of China (Grant Nos. 30400086, 30770285, 30700068) and Key Project Program of National Natural Science Foundation of China (Grant No. 60535020)