• UFRJ Nautilus

Choosing Materials for the Structure of our AUV - Part 1

Updated: May 7


In order to create the AUV project, choosing the right materials is extremely important, as they interfere not only in the functionality of the robot, but also in the team's score in RoboSub, the competition we participate in. For example, each material chosen brings a weight to the structure of the AUV and, the lower the weight, not only is a higher score attributed, but it also facilitates the transport of the robot.


In the image below it is possible to see how the weight of the AUV can lead to the team's final score, making clear the importance of a careful analysis of the different materials available for the construction of the robot structure.


Table of weight-related points on RoboSub

A correct choice of materials also ensures tightness, which makes our electronics safe. In terms of functionality, the right material provides a better use of the images captured by the cameras, allowing RoboSub tests to be carried out.


The article will be divided into two parts, given the length of the content; in part 1 we talked a little bit about acrylic and aluminum.


Acrylic:


Our current robot has acrylic hulls. The main hull is where we put the electronics, the cameras and the cover with the connectors; in addition to the battery attachment, which is smaller than the main hull, but equally important. For this reason, it is extremely important to ensure the tightness of these parts, as any water that reaches the interior of the hulls can compromise the integrity of the electronics.


Acrylic was chosen for its high transparency rate (approximately 93%), which allows the cameras to be able to capture images that will be recognized by the robot's software. In addition, it is a material resistant to distributed stresses, as is the case when it is under water.


In contrast to the benefits, acrylic tends to break as soon as there is a crack on its surface. Even taking this fact into account, the material is interesting for the team, since it doesn’t scratch often, so the effort needed to crack and, consequently, break, would have to be huge, an example would be to cut the acrylic with the wrong tool.


Acrylic Main Hull, with electronics inside and cover with connectors

Aluminum:


We use naval aluminum on the rods that hold the Main Hull, on the movable cover where the connectors are located, and on the AUV frame with the rods that are made of the same metal. Marine aluminum is the type of aluminum plate used in projects in the marine industry.


The singularities of aluminum are great and make the metal widely used in industry. In this way, it became one of the most sought-after metals for various Engineering projects and other services. Aluminum has a higher performance and characteristics in the wide range of its use, bringing with it enormous applicability in relation to other metals.


Some of the differentials of aluminum are: durability, offering resistance to AUV; lightness; it is resistant to corrosion, an important aspect analyzed, since it frequently comes into contact with water; flexibility; beauty; possibility of being recycled and reused; in addition to resistance, and although it is very malleable, we can see aluminum in many rail, plane and vessel transports due to its potential for tensile strength.


BRHue assembled with the aluminum structure

In any project the team works on, 3 important questions are asked: What is the project itself? What characteristics does this project need to have? What elements/materials will be used to obtain such characteristics, benefits and efficiency?


Thus, the study of materials science is extremely important in any project. Since antiquity, materials and substances mark eras, as each discovery is an innovation with new possibilities for application, which has led the development of Humanity. From this study, the team was able to select the most effi