Many animals have the natural ability to move on various surfaces,such as those having different roughness and slope substrates,or even vertical walls and ceilings.Legged animals primarily attach to surfaces using claws,soft and hairy pads,or combinations of them.Recent studies have indicated that the frictional forces generated by these structures not only control the movement of animals but also significantly increase the reliability of their attachment.Moreover,the frictional forces of various animals have opposite characteristics and hierarchical properties from toe-to-toe and leg-to-leg.These opposite frictional forces allow animals to attach securely and stably during movement.The coordination of several attachment(adhesion)modes not only helps animals adhere,which would be impossible in single mode,but also increases the overall stability of the attachment(adhesion)system.These findings can help the design of highly adaptable feet for bionic robots in the near future.
Studying the locomotive behavior of animals has the potential to inspire the design of the mechanism and gait patterns of robots ("bio-inspired robots"). The kinematics characteristics of a spider (Ornithoctonus huwena), including movement of the legs, movement of the center of mass (COM) and joint-rotation angle, were obtained from the observation of locomotion behaviors recorded by a three-dimensional locomotion observation system. Our results showed that one set of the stance phase consists of four legs, which were leg-1 and leg-3 on one side and leg-2 and leg-4 on the other side. Additionally, two sets of the stance phase comprised eight legs alternately supporting and driving the motion of the spider's body. The spider primarily increased its movement velocity by increasing stride frequency. In comparison to other insects, the spider, O. huwena, has superior movement stability. The velocity and height of COM periodically fluctuated during movement, reaching a maximum during alternation of leg phase, and falling to a minimum in the steady stance phase. The small change in deflection angle of the hind-leg was effective in driving locomotion, whereas each joint-rotation angle of the fore-leg changed irregularly during locomotion. This research will help in the design of bio-inspired robots, including the selection of gait planning and its control.
WANG ZhouYiWANG JinTongJI AiHongLI HongKaiDAI ZhenDong
The study of the movement behavior of geckos on a vertical surface, including the measurement and recording of the reaction forces as they move in different directions, plays an important role in understanding the mechanics of the animals' locomotion. This study provides inspiration for the design of a control system for a bionics robot. The three-dimensional reaction forces of vertical surface-climbing geckos (Gekko gecko) were measured using a three-dimensional force-sensors-array. The behavior of gecko as it moved on a vertical surface was recorded with a high speed camera at 215 fps and the function of each foot of a gecko are discussed in this paper. The results showed that the gecko increased its velocity of movement mainly by increasing the stride frequency in the upward, downward and leftward direction and that the speed had no significant relationship to the attachment and detachment times. The feet above the center-of-mass play a key role in supporting the body, driving locomotion and balancing overturning etc. The movement behavior and foot function of geckos change correspondingly for different conditions, which results in safe and effective free vertical locomotion. This research will be helpful in designing gecko-like robots including the selection of gait planning and its control.
WANG ZhouYiWANG JinTongJI AiHongZHANG YueYunDAI ZhenDong
The 3-dimensional interactions between toes of a gecko and substrates (ceilings or walls) were measured when it moves on ceilings or walls by using a 3-dimensional force measuring array,and the correspondent morphology of the gecko toes was recorded by a high speed camera.The study aims to understand the relationship between adhesive and shear forces generated by the toes of the gecko and the locomotion behavior when it walks on walls and ceilings.Results showed that shear force is along the toe-only 12.6° and 3.1° away from the toe for wall-climbing and ceiling-crawling,respectively while the adhesion is big enough to balance the body weight and moment.The shear forces generated by the first and the fifth toes are in opposite directions;this redundant force increases the reliability of adhesion and stability of locomotion.The support angles of toes are equal approximately for ceiling-crawling and wall-climbing.The study greatly inspires the design of a gecko-like robot.
WANG ZhouYi1,2,GU WenHua1,2,WU Qiang1,2,JI AiHong1 & DAI ZhenDong1 1 Institute of Bio-inspired Structure and Surface Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China
