Design & Technical Specifications
Electronics Enclosure and Connector Box
It was important to us to be able to work on the electronics enclosure separately from the chassis. Because of this, we utilize a center connector box where all of our thrusters and sensors route to. We use Blue Trail Engineering connectors for their cost and size to be able to remove the entire assembly without it being connected to anything on the chassis. The connector box also doubles as a heat-sink, given that it is constantly touching the water and being cooled. The dual enclosure design also allows us to keep everything symmetrical, and the buoyancy neutral.
Fully Modular Chassis
Our custom-designed modular chassis allows for a variety of operations such as quick-swapping sensors, or repairing broken components quickly and efficiently. Not only is the chassis fully customizable, it is made out of four aluminum tubes which allows the entire chassis to be light and cheap. Hardware can be installed using shaft collars, allowing almost anything to be mounted.
Thruster Mount Assembly
Our custom thruster mount assembly is used for a variety of things on Nautilus. Nautilus has four vertical thrusters and four horizontal thrusters, angled 45 degrees. This allows us to have six degrees of freedom and complete stability and control over Nautilus. The thruster mounts ensure that the motors are rigid and their position is precise to ensure stability and control. The mounts also act as a device to keep the chassis rigid, as well as a hoisting point. There are plans to perform structural analysis on the mounts in order to remove excess material and save on weight.
Custom Motor Controller Board
This year, we plan on
developing our own PCB for driving the ESC’s for the motors. The reasoning for
this is to have better cable management, and power control over all of the
motors on the sub. The motor controller board will have a microprocessor
programmed with Arduino that will monitor the voltage being supplied to the
motors, and will cut off power to the motors if the voltage is surging or if
the battery is running too low.
Main Component list:
· ATSAMD21G18 ARM Cortex M0+
· Adafruit Ethernet FeatherWing
· 20 PWM ports
· USB & USB C connector
· ROS capability
In total, the device should run on 10-12 volts for processing the input data and regulating the output voltage to the ESC’s.
Ground Control Station Concept
For future competitions, we plan on making an adaptable ground control station that can be used to control current and future submersibles for the club. The case for the ground control station will be a Pelican Case, which will be powered by a battery for more portability. This project will not be implemented for this coming competition, but we hope that it will be a worthwhile investment in the future for the club to continuously use in the future.
· Tele-op Mode
· Estop function
· Go home functionality
· Demo mode capability
· Program macros
· Electronic monitoring
· Auditory notifications
· Telemetry data
This ground station would make testing of our current and future projects much easier to conduct, proving more real time data and ease of access to data collected during tests. Because of this, we want to go all in on making the ground station as best as we can so it will stand the test of time. Dual monitors, 2 microcontrollers, an array of tether connections and multiple smaller LED displays are just the tip of the iceberg when it comes to what we plan on incorporating in the ground control station.
We are in the process of setting up the proper software on the NUC in terms of MAVROS and MAVLINK. This is so we can create communication between the Jetson, our image processing hardware, and the NUC, our primary processing and motor functions hardware. MAVROS is what we use for inter-ROS communications, and MAVLINK is the messaging protocol for unmanned vehicles, such as Nautilus. Together, they create a platform for efficient and capable movements in our robot.
Through these communication protocols, we are striving to build autonomy for our vehicle. This autonomy will allow for recognition-based movement triggers, giving Nautilus access to 6-DOF translations and enough independence to navigate aquatic environments.
Cuttlefish, our partner for Nautilus, is mainly intended as a testing/training platform. Cuttlefish is a BlueRobotics BlueROV 2 retrofitted with their Heavy Configuration add-on, as well as a Ping360 Sonar (not pictured). Because everything on Cuttlefish is already pre-configured, it allows the team to test hardware and software easily and efficiently. Some future goals for Cuttlefish is to utilize it as a competing sub to partner Nautilus. There are plans to incorporate data communication between the two so that Cuttlefish can take advantage of the sensors on Nautilus.