CAVERNAUTE: a design and manufacturing pipeline of a rigid but foldable indoor airship aerial system for cave exploration

Abstract

Airships, best recognized for their unique quality of payload/energy ratio, present a fascinating challenge for the field of engineering. Their construction and operation require a delicate balance of materials and rules, making them a compelling object of study. They embody a distinct intersection of physics, design, and innovation, offering a wide array of possibilities for future transportation and exploration. Thanks to their long-flight endurance, they are suited for long-term missions. To operate in complex environments such as indoor cluttered spaces, their membrane and mechatronics need to be protected from impacts. This paper presents a new indoor airship design inspired by origami and the Kresling pattern. The airship structure combines a carbon fiber exoskeleton and UV resin micro-lattices for shock absorption. Our design strengthens the robot while granting the ability to access narrow spaces by folding the structure - up to a volume expansion ratio of 19.8. To optimize the numerous parameters of the airship, we present a pipeline for design, manufacture, and assembly. It takes into account manufacturing constraints, dimensions of the target deployment area, and aerostatics, allowing for easy and quick testing of new configurations. We also present unique features made possible by combining origami with airship design, which reduces the chances of mission-compromising failures. We demonstrate the potential of the design with a complete simulation including an effective control strategy leveraging lightweight mechatronics to optimize flight autonomy in exploration missions of unstructured environments.

Figures (21)

• Figure 1: Interaction between the different requirements in the case of an aerostat. There is a mutual dependency between the multidisciplinary criteria requiring the use of a design methodology.
• Figure 2: Origami folding pattern. Valley creases are shown in dotted green and mountain creases in solid blue.
• Figure 3: Folding motion of a Kresling pattern ($n = 7,~m=2,~\lambda=0.9$). Folding follows a shearing movement. Due to segment symmetry, there is only pure translation for each bi-segment.
• Figure 4: Kresling geometrical parameters of one segment ($n = 6,~m=1$). $\alpha$ is the angle of rotation to unfold the geometry between the folded (0) and unfolded (1) state. The valleys are in green and the mountains in blue. $\alpha_{(0)} = 2 \lambda \gamma$ and $\alpha_{(1)} = 2(1-\lambda)\gamma~\forall \lambda > 0.5$
• Figure 5: Evolution of the length of $h$ and $b$ as a function of the bending angle $\alpha$. With the geometric description, the diagonal $d_g$ and the sides of polygons $s$ do not vary as a function of $\alpha$. However, this variation in $b$ creates a constraint that can be represented in Fig. \ref{['fig:energy']}