Mechanical System
Overview
Much of Onyx is based on Græy (our 2020-2023 AUV), and much of Græy is based on Orange (our 2019-2020 AUV), so we continued to use 80/20 extrusions for the base construction of the frame. Utilizing 80/20 extrusions provides us with better modularity with respect to the construction of our AUVs. While 80/20 extrusions may not be as compact as alternate options, like CNC waterjet parts, their quick assembly and cost efficiency allowed us to deliver within a tight schedule. Furthermore, this system’s modularity allowed us to rapidly make crucial modifications. For example, we fixed an unequally distributed buoyancy on Græy by shifting the positions of its two enclosures. With the 80/20 build system, we can use our manufacturing method of 3D printing to create accurately and properly toleranced parts that interface well.
Torpedo Launcher
Before designing the torpedo launcher, we utilized a robust design matrix to choose a design that would give us a working proof of concept that could launch torpedoes as early on in the season as possible. This would give us more time to test and familiarize ourselves with the mechanics of torpedoes and launchers, being new to the system. For this reason, we chose to use a 3D printed simple spring and latch mechanism powered by an underwater servo which would serve as the basis for testing our prototype torpedoes.
Gripper
The claw consists of the Newton Subsea ROV gripper base actuator with modified jaws fabricated through fused deposition modeling (FDM). The jaws were designed according to the game piece geometries, with an outer segment for manipulating chevrons and an inner segment for the bin handle. To make alignment and acquisition easier, the gripper is mounted on a linear slide rail with a magnetic quick-release match and will be deployed below the sub at the beginning of each run.
External Camera
We utilized the OAK-D family cameras this year. They are capable of processing/computing machine learning model code onto the camera itself. We have two cameras within our main enclosure, one forward facing, one downwards facing. We saw the control benefits with the addition of a third external camera to provide a visual on whether the gripper was able to pick up competition elements, a view not afforded to the team through just the downward or forward facing cameras. For our external camera we utilize an OAK-D POE camera as water blocking 8 strand cables are readily available for POE but 24 strand versions were not for the USB-C connection required for a smaller OAK-D Lite camera. We kept the manufacturing process simple with the number of operations low for the external camera enclosure.
Marker Dropper
We began exploring different design options for the marker dropper by creating a trade study of different designs. Doing so allowed us to rank each design's attributes and select the most optimal design to go with. Our requirements for the marker dropper were to be able to drop two markers separately with only one servo while reducing the footprint as much as possible. We went with the Kyutech Kyubic design due to its weight, minimal size, fabrication cost and reliability. Our first design implemented a 2000 Series Dual Mode Servo, control arm and barrel that holds two spherical markers.
Our design needs to function underwater so we used the Blue Trail Engineering Underwater SER-2000 Servo Enclosure. We used 3D printing to complete rapid prototyping initiatives to iterate and improve our design. We created dry and water unit tests using Arduino for performance verification.
DVL Enclosure
The DVL (Doppler Velocity Logger) was a late addition that was provided by Alan Kenny and his professional engineering team at Kenautics, Inc around March 2023 nearly 2 months before competition. The team explored manufacturability feasibility as well as implemented simulation analysis to risk reduce and verify our design assumptions.
