摘要
壁虎的脚掌上具有脚爪和刚毛两种附着器官,两种器官具有不同的附着机制,二者协同作用使壁虎具有在任意粗糙度的竖直墙面和天花板上自如运动与附着的能力.将壁虎脚掌上的脚爪去除后,放置在14种不同粗糙度的竖直的砂纸表面,以研究壁虎仅依靠刚毛时的附着能力.研究结果表明,仅仅依靠刚毛附着时,壁虎在各类砂纸表面的滑移速度、内收速度等存在差异性.滑移速度随着砂纸表面上颗粒直径与间距比值增大而减小,表面粗糙度并不是影响黏附性能的直接原因,其黏附性能由刚毛尖端末梢与砂纸表面的接触面积决定.研究壁虎脚掌刚毛在不同粗糙度的竖直表面的黏附性能,可以为设计基于仿壁虎刚毛黏附的爬壁机器人提供参考.
Locomotion is the basis of predation, escape, reproduction for animals. Geckos, spiders and insects run and climb with exceptional speed, strength and agility for their size, representing in many respects an ideal model system for the study of terrestrial locomotion. Biologists make comparative biology study with animals to develop a deeper understanding of the foundmental biomechanical design rules common to all legged organisms. Engineers look to animals＇ locomotion for design principles to improve the performance of legged robots including wall-climbing robots and other complex systems. Claws and setae are two kinds of adhesive devices in geckos＇ toe pads. These two devices can adhere on surfaces depending on different attachment mechanism. Synergistic action between these two devices makes geckos freely move on vertical walls and ceilings with arbitrary roughness. The interaction of claws with a substrate is determined by the roughness of the substrate, the friction coefficient between the claw and the substrate, and the relative dimension between the claw and the substrate. The stability of the interaction depends on the mechanism of mechanical inter-locking. The adhesion of geckos＇ setae is thought to be due to dry adhesion, which is generated by van der Waals force. The key parameters for the setae adhesion here is the distance between the terminal part of the setae and the substrate, which is in the range of a few nanometers in order to generate van der Waals forces. In addition that the microstructure of gecko setae affects to the adhesion performance, the morphology of substrate surface also plays an important role on the adhesion performance. Geckos with claws amputation were placed on 14 grades of vertical sandpapers to study setae＇ adhesive ability. The ratio of particles＇ diameter to distance on the surface of sandpapers was calculated. According to the ratios, 14 grades of sandpapers were classified into three new grades by the Q cluster analysis method which principle is that the difference between two neighbouring grades is the smallest among all grades. On the surface of sandpaper which the ratio is relatively smaller, geckos will slip down and try to make transverse adduction, even adjust its posture to keep adhering on the substrate. The maximum friction force between gecko spatula and sandpaper was calculated by the contact area. Then the relationship between the maximum friction force and adhesive force was also deduced. The results show that slipping velocity, adduction speed of geckos on all grades of sandpapers surface are different. Slipping velocity decreases with the ratio of particles＇ diameter to their distance on the surface of sandpaper increasing. The result from calculation is consistent with the conclusion from the experiments. The adhesive ability of geckos is determined by the contact area between the surface of the setae on the distal tip and sandpaper, and surface roughness is not a key factor. The study of adhesive performance of geckos setae can contribute to the design of wall climbing robot based on the adhesion of gecko-inspired setae.
出处
《科学通报》
EI
CAS
CSCD
北大核心
2016年第23期2578-2586,共9页
Chinese Science Bulletin
基金
国家自然科学基金(51375232)
江苏省自然科学基金(BK20141410)资助
关键词
壁虎
附着
粗糙度
刚毛
砂纸
gecko
adhesion
roughness
setae
sandpaper
