Locomotion behavior and dynamics of geckos freely moving on the ceiling

Abstract

To understand the mechanical interactions when geckos move on ceiling and to obtain an inspiration on the controlling strategy of gecko-like robot, we measured the ceiling reaction force (CRF) of freely moving geckos on ceiling substrate by a 3-dimensional force measuring array and simultaneously recorded the locomotion behaviors by a high speed camera. CRF and the preload force (F P ) generated by the geckos were obtained and the functions and the differences between forces generated by fore-and hind-feet were discussed. The results showed that the speed of gecko moving on the ceiling was 0.17-0.48 m/s, all of the fore-and hind-legs pulled toward the body center. When geckos attached on the ceiling incipiently, the feet generated a very small incipient F P and this fine F P could bring about enough adhesive normal force and tangential force to make the gecko moving on ceiling safely .The F P of the fore-feet is larger than that of the hind-feet. The lateral CRF of the fore-feet is almost the same as that of the hind-feet's. The fore-aft CRF generated by the fore-feet directed to the motion direction and drove their locomotion, but the force generated by the hind-feet directed against the motion direction. The normal CRF of fore-and hind-feet accounted for 73.4% and 60.6% of the body weight respectively. Measurements show that the fore-aft CRF is obviously lager than the lateral and normal CRF and plays a major role in promoting the fore-feet, while the hind-feet of the main role are to provide a smooth movement.The results indicate that due to the differences of the locomotion function of each foot between different surfaces, the gecko can freely move on ceiling surfaces, which inspires the structure designing, gait planning and control developing for gecko-like robot. 3-dimensional locomotion reaction force, dynamics, ceiling, 3-dimensional force measuring array, geckoCitation: Wang Z Y, Wang J T, Ji A H, et al. Locomotion behavior and dynamics of geckos freely moving on the ceiling. Robotics is one of the major application areas of modern bionics [1]. Robots, which are used in un-structured circumstance, especially the robots with TDOF (Three Dimensional-terrains Obstacle Free-such as running on floors, climbing on walls and moving on ceilings) locomotion ability are the most challenged high technology and become a mark of the level of technology and the comprehensive national strength. To learn from and obtain the inspiration from nature has become a valuable means in developing new robots. Scientists would like to discover how animals have done in TDOF moving and what mechanism and key technique could be transferred from nature to technology to *Corresponding author (email: zddai@nuaa.edu.cn) develop the TDOF robots. During the past years, Autumn, Bharat, Bergmann have carried out a lot of researches on the structure and micro-structure of gecko feet [2-4], mechanisms of adhesion [3,5] and adhesive strength [4,6-8]. Damme et al. focused on the locomotion kinematics of gecko moving on the horizontal and verti...

Vertical locomotion in the arboreal salamander Aneides vagrans

“…Many species of gecko are specialized to traverse vertical and inverted terrains (Autumn et al, 2006;Wang et al, 2015Wang et al, , 2020. While A. vagrans abandoned the diagonal couplet gait when walking across vertical surfaces, Gekko gecko and Hemidactylus garnotii have been recorded using a diagonal couplet gait regardless of direction or incline (Autumn et al, 2006;Wang et al, 2010;Zaaf et al, 2001); however, the grounddwelling Eublepharis macularius, was recorded switching to a single-step walk when locomoting vertically (Zaaf et al, 2001). The ability to cling using strong adhesion has allowed geckos to navigate otherwise unreachable habitats (Thompson, 1918), and may explain the use of consistent gaits regardless of substrate orientation.…”

Use of opposite frictional forces by animals to increase their attachment reliability during movement

“…Animals make intelligent use of the different adhesion modes of their feet to stably attach to different substrates. Geckos catch surface particles with their claws on rough surfaces while they use their setae to attach to smooth inclined surfaces [8,26]. Gampsocleis gratiosa [30] creeps along vertical glass using flexible pads, where the tangential forces (friction forces) are much larger than the normal adhesive forces because they can insert pad cuticles into the microstructures of the glass surface.…”

“…In addition, the research regarding the climbing ability of geckos [8], tree frogs [33], and locusts [13] show that their left and right legs in the stance phase need to generate opposite lateral forces, or sometimes opposite shear forces, to increase the stability of the attachment on an inclined surface. This suggests the contribution of opposite forces at different scales, from the basic-level-toe-to-toe in geckos, claw-to-claw in beetles, and left-to-right projections in the soft pads of locusts-to higher-level legs between the left and right side of the animals.…”

“…In particular, many animals move with easiness in a variety of complex surfaces using highly evolved feet. For example, the ability of geckos [7][8][9], insects [10][11][12][13][14], and spiders [15,16] to move on different types of surfaces is valuable to bionic design. Moreover, the stability, flexibility, robustness, adaptability, and use of energy displayed by animals are still challenges for bionic robots [17].…”

Stiff skin, soft core: soft backings enhance the conformability and friction of fibre-reinforced adhesives

“…Think, for example, of the vastly different substrates (e.g. smooth leaves, wet rocks and dry bark) a tree frog can adhere to [2–5], the high velocity at which a gecko can move across vertical and overhanging substrates [6,7], and the countless substrate contacts undergone by the adhesive tarsal pads of a fly during its life time. Bioadhesion research aims to sharpen our understanding of the complex physico-chemical mechanisms that underlie this striking performance, which is relevant to both fundamental and applied scientific research.…”