| With development of modern society towards industrialization and urbanization, the work on the stiff wall becomes inevitable. The military missions executed in the urban environment, especially the streets, buildings, indoor wall environment are becoming more meaningful both for tactic and strategy in dealing with the situation of the world with frequent local conflicts and grim anti-terrorism. Therefore, it is important to develop wall-climbing robots with "three-dimensional-obstacle-free"(TDOF) ability, which can reduce the risks of jobs on the wall, increase working efficiency and perform multi-tasks. The conventional technology of wall-climbing robots uses the methods of gripping, electromagnetic, suction, and static electricity, to realize TDOF, This technology is fully developed and widely used in rescuing, construction, municipal engineering, petrifaction, shipbuilding, aeronautics, nuclear plants, etc. However, the wall-climbing robots made by these methods have disadvantages, such as in low compatibility for different surfaces, high energy consumption, large size, and high noise. They are difficult to be made miniature and light-weighted to perform tasks in narrow areas. In the nature, the gecko is the master of wall-climbing. Their exquisite structures of the digital surfaces provides inspiration for man to fabricate bio-inspired dry adhesive and new wall-climbing robots.This dissertation mainly focuses on the research of the gecko’s dry adhesive mechanism as well as the design of bio-inspired wall-climbing robots. Firstly, a multi-scale directional adhesive model for the gecko’s seta is developed. The model is based on the uniform distribution assumption of the contact forces by using Eular’s inextensible elastica theorem. Secondly, a gecko’s lamellar model is established following the multi-scale gecko’s seta model, and then the gecko’s digital behavior is analyzed. Thirdly, the adhesion capacity of a gecko-inspired adhesive for application in wall-climbing robots is predicted and tested. Inspired by the gecko’s digital structure and behavior, a tank-like module-based, underactuated wall-climbing robot which can climb on the ceiling is designed and fabricated. The feature of the robot lies in its adjustable contact forces with the underactuated mechanism.The main findings and innovations of the research are summarized as follows:(1) The G’ gecko’s setal modell has been established considering the directional adhesion and multi-scale interaction. The setal model recreates the gecko’s directional adhesion, and can predict and interpret the behavior of the gecko’s seta in the attachment and detachment of the gecko.(2) The meaning of the G’ gecko’s digital behavior including digital gripping and digital hyperextension has been interpreted. Comparing with the work at home and abroad, the research has considered the role the multi-scale interaction plays in the attachment/detachment procedure. The directional adhesion model provides a tool for more accurate analyses in the G’ gecko’s digital behavior and dry adhesive mechanism for the future.(3) The capacity of the nano-scale adhesive array patterned with spherical surface has been predicted, including adhesive strenghth and effective adhesive energy, and tested under static/dynamic scenarios. Using this material, the adhesive tread for the bio-inspired wall-climbing robot has been fabricated, and used in the design and optimization of the wall-climbing robots. The array exhibits better adhesion than non-patterned arrays.(4) The under-actuated joint mechanism has been used in the design of the tank-like modular-based wall-climbing robot, inspired by the gecko’s digital structure and behavior. A prototype has been fabricated via 3D-printing technology. Comparing with robots at home and abroad, this research has optimized the prototype’s structure and realized the stable adhesion between the robot and the wall with the adjustable contact force.
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