종이 접기 구조 기반 지름 가변형 휠의 설계 및 제작

Abstract

A wheel-drive mechanism is simple, stable, and efficient, but its mobility in unstructured terrain is seriously limited. Employing a deformable wheel is one way to increase the mobility of a wheel-drive robot. By changing the radius of its wheels, the robot is able to pass over not only high steps but also narrow gaps. The thesis propose a novel design of a variable-diameter wheel using an origami-based soft robotics design approach. Soft robots attain infinite degrees of freedom from the soft materials of which they are made (e.g., elastomer and fabric), thereby achieving unique characteristics: dexterity in motion, deformability, and adaptability to environments. Using soft materials for a variable-diameter wheel accompanies two advantages – high deformability and ability to absorb impacts, but inadequate stiffness and excessive degrees of freedom can impede a wheels functionality. The key idea is to overcome these deficiencies by making the wheel structure from a soft material to which an origami pattern has been applied, which reduces the materials excessive degrees of freedom and increases the structures stiffness. The proposed design provides three key advantages. First, the structure can be built without many mechanical parts or a complex assembly process. Second, an origami structure can have high stiffness and impact capacity compared to its weight. An origami structure is composed of compliant folding parts and facets, so the whole structure can perform as a shock absorber. Third, an origami structure is scalable. The structure generates a joint by folding, and this reduces friction between links. The simplified assembly process using origami structures reduces the difficulty in assembling small-scale parts. The thesis presents a design and fabrication method of the transformable wheel and provides a comprehensive analysis of the wheel structure. Also, the thesis contains the robot design with the wheel transformation mechanism. The wheels diameter can change from 30 mm to 68 mm, and it is light weight at about 9.7 g. Although composed of soft materials (fabrics and films), the wheel can bear more than 400 times its weight. The robot was able to change the wheels radius in response to terrain conditions, allowing it to pass over a 50-mm gap when the wheel is shrunk and a 50-mm step when the wheel is enlarged.