AUV Specification:
Weight (in Air)
57.3202 lbs. (26 kg)
Hull or waterproof Enclouser
15.6"x11.6” x5.6"
Dimensions(inches)
26.2”x21.67”x11.8”
Propulsion
8x Blue Robotics T200 Thruster
Power
2x 14.8 5400 mAh LiPo Batteries
Underwater Connections
Ethernet and fathom X
Cameras
2x Blue Robotics 1080 P Low light cameras
Navigation Sensors
Pressure Sensor (Bar 30 Depth Sensor) INS (Vectornav VN200)
Main Computer
Jetson Orin Nano Developer Kit, GPU: NVIDIA Ampere architecture with 1024 NVIDIA® CUDA® cores and 32 Tensor cores. CPU: 6-core Arm Cortex-A78AE.
Embedded Computer (Control)
AT mega 2560 & Pixhawk Flight Controller
Bracu DUBURI 4.1 Mechanical System
The body of the hull is built with Marine 5083 grade aluminum. Because of its low density, high strength-to-weight ratio, resistance to corrosion, and good thermal conductivity, this specific aluminum was chosen. The top enclosure along with the front and bottom camera openings are sealed with acrylic windows having brass frames. Although this gave the AUV an upper edge in terms of weight there was a significant rise in manufacturing cost. Further- more working with aluminum in particular required expert involvement in terms of welding which also increased production time.
Hull Design Of Duburi 4.1
In terms of this design Duburi has now went ahead with a octagonal shape compared to the previous year’s hexagonal shape. The design choice was made keeping previous year’s findings in mind. The flat surface in a pentagon shaped design in previous years AUV led to increased drag when it tried to go in reverse which greatly reduced the AUV’s efficiency and put excessive yet unnecessary load on the rover to reach the same level of compe- tence compared to this year’s design. This year the hydrodynamic hexagonal shape allowed equal flow over the AUV’s surface reducing turbulance. It also massively reduced the drag caused when operating in reverse. Although to keep the rover hydrodynamic in this year’s design the outer support structure used to mount thrusters was removed hence resulting in the thrusters being more prone to physical damage in an event of collision.
To gain the style points we have opted to make some changes in our structure of the AUV. The position of the Depth thrusters have been changed as we faced issues stabilizing our pitch. Being so close together as before caused a never ending oscillation which caused the vision system to lose lock on the visual object, though not a major issue we fixed this problem.
The depth thruster being so far away from the Center point will make the bot roll and pitch more efficiently because the more you move away from the center the less force is required for rotating in any axis. To make the AUV more aerodynamic a shell is designed and implemented.
TORPEDO DESIGN OF DUBURI 4.1
Our focus was to enable a straight launch of the torpedo from a long distance. So our core focus was on the shape and launching mechanism. As we have got real good results with rubber bands, the whole system is based upon such methodology. As the torpedo is locked as potential force is stored and a locking mechanism is used to lock it in place when the solenoid is triggered it launches straight.
Grabber DESIGN OF DUBURI 4.1
Our own design and custom CNC aluminum grabber. A Dc motor is used to push a rod which opens or closes the End effector. Current Sensor is used to Determine whether the grabber is open or closed. The DC motor is housed inside a waterproof enclosure. With only terminal wire controlling power delivery.
Dropper DESIGN OF DUBURI 4.1
Door lock solenoid is used for locking and unlocking the dropper. An we used gravity to our advantage and designed a simple system that releases the dropper signal is received.
Bracu DUBURI 4.1 Electrical Architecture
Power-flow OF DUBURI 4.1
Two separate power sources are used to power the whole system and thruster. To Control the power supply 2 Kill switches are required.
Source 0 is used for Powering thrusters. Source 1 is used to power every other thing in the bot. Dropper, Torpedo, Grabber, powered from Source 1.
Source 1 Explained: The buck converter powers the Jetson nano, Pi 4, Fathom X, switch with 5V and Jetson Orin (Not on the Picture Below), Nucleus 1000, Light with 12V.
NAVIGATION SYSTEM
Duburi uses a Vectornav VN-200 GNSS aided INS. That ensures maximum performance and efficiency. The INS combines 3-axis gyros along accelerometer and magnetometer. The results are further improved by applying advanced Kalman filters that ensure very low deviation of values over an extended period of testing.
Micro-controller
Previously Duburi relied on 8bit ATMega2560 micro-controller for its control unit. Which had ma- jor drawbacks such as high latency,slow processing and most importantly lacked real time engagement required for optimal performance. This year the issue is solved by relying on 32 bit STM32 based system Pixhawk further integrated with Vectornav VN200 INS,ensuring greater performance and reliability with real time communication.The faster pro- cessing speed has massively increased the AUV’s overall performance.
Power Distribution Board
Our approach or motto was to keep the main electrical circuit/system as simple as possible which requires less debugging and easier management in time of critical situation. A single wire takes power from the buck converters and distributes them to devices such as pi 4/Jetson or network stack.
Bracu DUBURI 4.1 Software Architecture
Simulation
We have built a new and robust unity based technical testing environment. This allows the user to interpret and test codes prior to real world testing. The environment consists of completely rendered version of the competition ground and props. This allows us to estimate probable bugs prior to water testing. This allows the team to follow an Extreme Programming approach to development.
Interfacing
Duburi's microcontroller board, the Arduino Mega, strikes at the core of its operation. It functions as a control surface between the sensor payload's inputs and the actuators and end effectors on the Duburi, it manipulates the Duburi's thrusters in line with the data signals it receives to maintain steady locomotion.
UNDERWATER OBJECT DETECTION
In our AUV we have implemented visual homing which figures out the detection center, then calculates the offset. Then using a calculative approach we fix the AUV’s position to align with center of the computer vision detection. The AUV constantly holds the center position by keeping the center of the detection as the point of interest.
AUTONOMOUS MANIPULATION
our AUV s capable of fully autonomous manipulation of objects. We have implemented grabber system, dropping marker, and torpedo launching system. Our software is capable of detecting the object, aligning the AUV with the object, and then grabbing the object. The AUV can also drop the marker and launch the torpedo autonomously.