Nauti by Nature

Overiew

Our team has designed and built the Zero-Ingress, Lightweight Uncrewed Scuttlebutt (ØILUS), a watercraft engineered to navigate up to 6-inch-deep blue waters. Accompanying the ØILUS is the Nautical Electromechanical Device for Mobile Operation (NEDMO), which includes two key components: the Nonspecific Assignable Vessel Controller (NAVCON) and the Free Uninterrupted Energy Laboratory Console (FUELCON).

The ØILUS, operated wirelessly by our team, is deployed in the Shimmering Extent of Ambition (SEA), where it engages in dynamic challenges. During operation, each team controls their ØILUS to navigate the waters and attempt to sink the Towed External Non-Directional Rigs (TENDRs) of opposing ØILUSs. This project showcases our expertise in marine robotics and remote operational technology, emphasizing strategic control and innovative engineering.

The Game

At the beginning of each game, participating ØILUSs are paired with NEDMOs either randomly or as decided by the teaching team. All TENDRs are emptied and placed afloat on the SEA before the start of a game round.

Each game round involves the following:

Objective: Each ØILUS attempts to sink the TENDRs of all other operational ØILUSs.
Duration: The round continues in real time with no turn-taking until only one ØILUS has a floating TENDR left.
Persistence: If a craft’s TENDR is sunk, it can still pursue and attempt to sink the TENDRs of other ØILUSs, but the sunk TENDR must remain sunk for the entire game round.

The full project description, including the requirements, can be found here.

Gameplay

Ganeplay.MOV

Moving.MOV

Solution

In our solution, we aimed to create a ØILUS that resembled a pontoon, known for its reliability in water. The general shape consisted of two pink foam logs with a channel down the center for buoyancy and stability. Additionally, we incorporated a full perimeter of grey foam to further enhance stability, buoyancy, and crash absorption. For propulsion, we chose a single motor controlling a single propeller leading to a single rudder, as we believed this to be the simplest yet most effective design to implement. For our splashing mechanism, we settled on a pump and nozzle that intakes water from the center channel and sprays it off the bow. We used a flagpole for both displaying our team number and attaching the tender line, thinking this dual use would simplify the design. For the pairing status indicator, we used a servo that lifted a retired part from a previous design as a memorial to the pontoon.

For the full code, electrical schematics, and mechanical design, visit the ØILUS page.

For the design of the NEDMO, we started with our FUELCON. We aimed for a large motion where a Red Solo Cup is taken out of a holder, liquid is drunk from it, and then it is placed back in the holder. This motion, taking more than 2.5 seconds, is a fun and traditional boating pastime. We successfully made cupholders to sit in the bulk of our FUELCON, with limit switches at the bottom that were only triggered when there was enough liquid in the cup to depress them. To pair to an ØILUS, a potentiometer was mapped to select a boat, and the red arcade button was used to send the pair message. The fuel level of the paired ØILUS was displayed by a servo with 75° of resolution.

Our NAVCON was redesigned after the initial design failed. We created it to be as simple as possible for ease of use. We used three inputs for the NAVCON: two sliding potentiometers and one joystick. The bottom linear potentiometer controlled the rudder position, the vertical linear potentiometer controlled the motor speed, and the joystick was used for the pitch and shooting of the splashing mechanisms.

For the full code, electrical schematics, and mechanical design, visit the NEDMO page.

Successes

A major success was the overall shape of our ØILUS. We were very pleased with the pontoon design and the buoyancy of the ØILUS. It was specifically designed to accommodate the many features that needed to be held within the hull, including the electronic casing, motor, servos, and flagpole. We built extra space to allow the foam to slip on and pre-fabricated holes for zip ties to fix it in position, which worked splendidly.

Our NAVCON was simple and easy to use. We were very happy with the sleek, slender design we achieved. The dual linear potentiometers allowed for ease of use, and the joystick was perfectly mapped to the splashing mechanism.

The large-scale motion of the FUELCON worked exactly as anticipated and added a fun element to our project. We found this implementation to be a successful and enjoyable part of our design.

Challenges

One significant challenge was the single motor drive system. The custom propeller we created was inefficient and caused water breakage when turned on. The fixed angle of the motor mount made it difficult to adjust the propeller’s position. Additionally, the rudder’s range of motion occasionally caused it to hit the propeller, reducing efficiency. Adding weights to the back of the ØILUS only marginally improved this issue, but it would have required a total redesign if time had permitted.

A delay in arrival of our initial pump forced us to pivot and find a new pump at the last minute. This last-minute change resulted in a less aesthetically pleasing and less efficiently integrated solution, as we had to tape the new pump to the top of the electronics box. Accessing the electronics box was also challenging, leading to frequent communication issues.

We faced challenges with the potentiometer used in the NEDMO for selecting the ØILUS controller. The non-linear nature of the potentiometer, designed for audio amplifiers, required us to remap the analog output values to the correct ØILUS. Despite these challenges, we were able to successfully implement the servo and arcade button for controlling the fuel level and sending pair messages.

Our initial design for the NAVCON, which aimed to mimic the design of a typical RC controller, failed, necessitating a redesign to simplify and ensure ease of use. The commitment to the initial design resulted in a significant waste of valuable time, but the redesign ultimately became a necessity.

Tips and Tricks

Mechanical

Find a Reliable Propulsion System: We noticed other groups using underwater thrust systems that worked reliably and effectively. Compared to our custom propeller and shaft through the hull, these systems were more reliable and effective, although more expensive.
Determine an Effective Waterproofing Method for Electronics: Tupperware is a great low-cost option for waterproofing, but it requires planning for the volume and organization of the electronics, as well as methods for sealing openings for wires and switches. We found that plumber’s putty is a great non-permanent option for sealing.
Prioritize the Splashing and Sinking Function: Many groups had creative ideas that didn’t involve a pump initially, but eventually, everyone ended up using one. Get a pump early and plan an effective spraying method.

Electrical

Simplify the Electrical System: Given the ØILUS’s proximity to water, keep the electrical system as simple as possible. Less hardware means fewer things to break.
Characterize Your Motor Early: Properly characterize your motor early and ensure that the rest of your circuit can drive it effectively.

Software

Standardize Communication Services: Create a standard service for communications to use, slightly adapted for both devices. Having these functions work similarly makes debugging much easier.
Build Incrementally: Implement one piece of functionality at a time to reduce the complexity of the problem and make troubleshooting easier.

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