Electrical Subsystem
Electrical Design
POWER BOARD
The Power Board manages the AUV's power distribution, thruster control, and kill switches.
It features voltage regulators, a Teensy 4.0 microcontroller, a dual battery input hot-swap controller, battery voltage sensors, thruster current sensors, water leak detection circuitry, and a two-stage kill switch system. The main kill switch cuts power to the thrusters, while the secondary switch can shut down the entire system in emergencies. In case of a leak, the microcontroller can also kill the system automatically. LEDs indicate powered nets and the active battery. The eight thrusters have 15A reset fuses to limit current draw. Dual-battery support allows for mismatched voltages, discharging the more charged battery first until balanced. The AUV can operate fully on a single battery, with a second battery extending mission duration. Current and voltage data are relayed through ROS to the Jetson and other embedded systems.
Electrical Design
DISPLAY BOARD
The Display Board, featuring an ILI9341 display controlled by a Teensy 4.0, facilitates critical information monitoring for the AUV.
The screen and Teensy communicate via the Serial Peripheral Interface (SPI) protocol. The external pressure sensor connected to the Display Board determines the AUV's depth and publishes this information to the Jetson using ROS. The board subscribes to multiple ROS topics to display crucial data, including battery voltages, position and orientation quaternions, depth, and the status of each thruster, DVL, IMU, cameras, and other boards. It enables visualization of subsystem status and battery discharge, and is positioned under the top side circular window for easy inspection.
Electrical Design
ACTUATOR BOARD
The Actuator Board features an onboard Teensy 4.0 microcontroller that is responsible for controlling the servo motors used in the grabber, dropper, and future torpedo subsystems. It can support up to 5 servo motor outputs and features servo current sensing circuitry. The current sensing on the Actuator Board helps monitor current draw but also senses contact for the grabber subsystem. The board receives a 5V power input from the Power Board and distributes it to the servos. Additionally, the board has 1A fuses for each servo and status LEDs. The Teensy communicates with the Jetson via ROS to send current sensing data and receive servo actuation commands.
Electrical Design
HYDROPHONE BOARD
The Hydrophone Board utilizes an STM32 Nucleo microcontroller to process signals received through the four external hydrophones. The hydrophones are connected to a filter amplification board that processes the pinger signals for the 3.3V STM32 analog-to-digital converters (ADC). The microcontroller employs a Fast Fourier Transform (FFT) algorithm to compute the frequency of the incoming sound waves and also saves the timestamp each hydrophone receives the signal. The frequency of the incoming sound wave and time differences between the hydrophones are relayed to the Jetson through ROS, enabling it to triangulate the position of the pingers relative to the AUV.