The GU Robosub Electrical Team is composed of students who are eager not only to apply what we learn in class, but to learn new things via hands-on experience with real world circuits. The Electrical Team works closely with the Mechanical and Embedded Systems teams in order to facilitate sensor and apparatus implementation.
So far we have successfully implemented a power distribution system, a thruster kill switch, a leak sensor, and wired communication between various sensors and components. We’re always looking for ways to improve Terrapene by adding new features and improving existing ones. Expand the sections below to see what exciting projects we’re working on right now!
The hydrophone project was designed to allow Terrapene to triangulate the location of a pinger in the pool. The location of the pinger is triangulated by using a system of 4 hydrophones. When a ping from the pinger reaches a hydrophone, it records the time at which the sounds reached the hydrophone. Knowing the speed of sound through water, it is then possible to use trigonometry to triangulate the direction of the pinger in relation to Terrapene. Terrapene would then move forward and recalculate the direction fo the pinger. Once the direction of the pinger is recalculated, Terrapene will adjust its course. Once the sound coming from the pinger reaches each of the four hydrophones at relatively the same time, Terrapene will then surface.
After the sound from the pinger reaches the hydrophone. The hydrophone outputs a signal that is sent through an amplifier. This signal is then digitized by the TI’s ADC. The TI then filters out the pinger sounds from the noise based on the frequency of the sound. The system is tested by using a waterproof speaker the receives a signal from an arbitrary waveform generator. Using this method we are able to simulate all of the possible frequencies that the pinger could use at the competition.
The sub is powered by three LiPO battery packs in parallel. Due to the nature of LiPO batteries, they have to be closely monitored to ensure that they stop being used before they reach critically low voltage. At best this permanently ruins the batteries and at worst it can start a fire.
Previously we have monitored the battery voltage via the mission control interface, but this has been inaccurate and cannot be done while in autonomous mode. To remove the need for a software connection, we are implementing a hardware low-battery indicator to flash an LED when the battery voltage drops below a threshold. We are also building a circuit that will cut power to the entire sub when the battery reaches a critically low level, so that even if the low battery indicator wasn’t seen, the sub will shut itself off in order to save the batteries. This will allow Terrapene to be used in a more autonomous setting without requiring constant supervision.
Terrapene loves the water, but the electronics in its hull really don’t. While leaks don’t occur often, they are not unheard of and we need to know when one happens. We built a Leak Sensor PCB using a milling machine that has connections for two water probes that will switch on an LED if either of them detects water. The board also has a signal output to let another circuit know that a leak has been detected. In the future, we hope to use one probe as a warning to turn on an LED, and the other as a critical signal to cut power to the thrusters, allowing Terrapene to float to the surface where its seal will be above the water line.
The embedded systems team is in charge of low-level control of the sub. From operating motors to interfacing with our RFID system, our team makes sure new and existing components can work with our sub. Whenever there is a new component added to the sub, it is our job to make sure the integration is seamless. We take the information from the mission computer and convert it into usable instructions for the motors and other devices.
The microcontroller: All of our major components are connected to the Texas Instruments TM4C123GXL microcontroller to send and receive information to our mission computer. This microcontroller is nice because it is a low power solution that provides the amount of customization we need at a low level. Using the TiveWare libraries, we have access to powerful drivers to control the microcontroller. To communicate with the mission computer, we have constructed a custom serial communication protocol to efficiently transmit all relevant information including current state information and desired control values.
The Mission Computer team develops the “brain” of the sub, the program that interprets data collected by the camera and the embedded system and determines what actions should be taken. Additionally, the Mission Computer team works on the mission control platform, which is a standalone program that communicates with the sub over ethernet to display sensor readings and allow for the sub to be controlled manually. Currently, the team is working on triggering preset missions through RFID tags and testing compatibility with a new version of the mission control platform.
The GU Robosub Mechanical Team is a group of innovative individuals who have a love for design and hands-on engineering. Our team strives to design, build, and maintain the outer and physical components of the Autonomous Underwater Vehicle (AUV).
During the year we work together to participate in brainstorming, researching, calculating, and testing to achieve our desired properties of the sub. Whether it’s building a new AUV from scratch or innovating our most previous one, you can always find more ways to go above and beyond on the mechanical team.
We also like to give an emphasis on improving not just our submarine, but our students as well. Our club members get a unique opportunity to get a headstart on their peers in several helpful resources and areas. SOLIDWORKS, 3D modeling and Printing, certification to use the tools in the Manufacturing Technology Center, hands on experience with tools and building, leadership opportunities, and community service are all things that we have been able to do and help teach our members within the GU Robotics Mechanical Team.
Each year GU RoboSub team strives to create an Autonomous Underwater Vehicle (AUV) that can perform against many obstacles at our yearly Robosub Competition and keep up with preparatory pool testing during the school year. Every summer we have the opportunity to participate in the international Robosub Competition held in San Diego. There we get to participate in genuine on-the-spot troubleshooting and get to gain a deeper understanding of how our teams have come together over the year and how to improve.
Given that we are a young team, we are very proud of our accomplishments over the past two years at competition.
RoboSub Competition 2018 with Exodus
RoboSub Competition 2019 with Terrapene