2020 - Dragon

2nd at 2020

RoboSub

working_on_final_assembly.gif

General Overview

Dragon is the team’s second AUV, designed to work in conjunction with Phoenix. She will have all the capabilities that Phoenix does, as well as a pneumatics system that allows for advanced manipulation. 

Mechanical 

Hull Design

Dragon has five smaller hulls instead of Phoenix’s three. Separating the hulls allowed members to separate the component systems they needed to work on without taking the whole robot with them. They include the thruster hull, pneumatics hull, computer hull, and battery hulls (x2).

Marker Dropper

Dragon’s marker dropper was designed from scratch this year to be simple, reliable, and efficient. We developed an initial prototype using a cardboard tube and pencils. From there, we were able to make a final design that uses PVC pipe and 3D printer PLA. It used PVC pipe and 3D printed PLA. The red tabs allow the markers to be easily loaded with one hand. Pneumatic pistons release the markers with 1 in of movement. The marker dropper had a perfect first trial run.

Projectile Launcher

The projectile launcher is 3D printed, easily loaded with one hand, and actuated by a pneumatic piston with 1 in stroke. When the projectile launcher is loaded, a spring is compressed behind the projectile. When a piston opens the hatch that restrains the projectile, the pressure is released and the spring propels the projectile forward. 

Custom Boards:

(Hover over for images)

Marker Dropper

Dragon’s marker dropper was designed from scratch this year to be simple, reliable, and efficient. It used PVC pipe and 3D printed PLA. The red tabs allow the markers to be easily loaded with one hand. Pneumatic pistons release the markers with 1 in of movement. The marker dropper had a perfect first trial run.

Main Board

The Main Board communicates similarly to the Main Board on Phoenix, by sending sensor information to the Jetson. The Jetson is an Embedded AI computing device that handles higher-level tasks such as mission management, outer control loops, network communications, vision processing, and data logging.

Sensor Fusion Board & Fiber Optic Gyro

While Phoenix utilized a single-axis FOG (Fiber Optic Gyroscope), Dragon was upgraded to a three-axis.  The Sensor Fusion Board receives data from the FOG and DVL, this data provides a sensor fusion algorithm to generate yaw, pitch, and roll.  This process generates a more consistent, accurate, and dependable source of information needed to complete game tasks.  

Pneumatics Board

The Pneumatics Board is used to control Dragon’s 8 solenoids. This board receives a command from the main board indicating which actuator to enable, during this process, telemetry data is sent back to the Main Board. This is accomplished by an N-channel MOSFET connected to each solenoid, in a low side switching configuration.

Motor Control Board

To control the motors, the Main Board runs the control loops that determine motor values based upon the given set points/inputs; this is dependent on which control mode is active. Motor values are sent to the Motor Control board, and these values are translated into PWM signals that are used to manage the motors.

Grabber

Dragon is fixed with a pneumatic grabber arm purposed to pick up objects underwater. Its design was inspired by Team Bumblebee from Singapore. The pneumatic piston moves with a 1-inch stroke of movement allowing the grabber claws to open 3.5 inches wide. The grabber arm can be mounted horizontally or vertically. The grabber had a successful first trial run.

Software

HSV Testing

For vision software, the team first began writing code to detect objects of a certain color, such as a red circle, using OpenCV and a HSV filtering technique.

The team then began writing software to detect more complicated shapes, like path markers, from footage from the previous competition

Image training

The team then began writing software to detect more complicated shapes, like path markers, from footage from the previous competition

Simulation

The testing simulator allows the team to test the ability of the AUV to navigate to a certain position determined by user input. One module reports telemetry data, while another is used to send the operation mode. Currently, work is being done to upgrade the simulator to allow the team to be able to test vision software prior to entering the water.

When we're not able to test in the water, we have a Unity-based 6 degree of freedom simulator that uses a physics model of the AUV to determine how it will react to motor efforts determined by simulated sensor readings

Testing

Grabber Test

The grabber’s grip strength is essential to the AUV’s ability to pick up objects. The grabber was tested by picking up wooden blocks.

Torpedo Tests

The density of the torpedo was adjusted to achieve the right buoyancy to make it fire straight consistently.

Board Communication Test

The mainboard(left) sends the current control mode to the motor board (right) and it’s LEDs will mimic the mode that is defined on the mainboard. The mimic in LED color and pattern indicates information is received.

Solenoid Test Program

The marker dropper, torpedo launcher and grabber arm all utilize pneumatic cylinders operated by solenoids controlled by the pneumatics board. A program was designed to test fire each solenoid one-by-one.

Marker Dropper Tests

The marker dropper was designed to be easily accessible and loaded quickly, it has been tested dozens of times without fail.

Hydrophone Test

A Subsonus hydrophone array was used to collect acoustic data at the TRANSDEC facility. The data obtained from the TRANSDEC will be used as a baseline to adjust for noise when using Subsonus .

Vacuum Leak Tests

Each hull is tested for leaks, first by a vacuum test and then submerged underwater, before being assembled to the rest of the AUV.

3D print test

All large 3D printed components were first manufactured as low-density draft prints to test fit

and functionality before being printed at higher infills in their final form.

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