Sprint #1 Recap – Bugs, bugs, and more bugs!

Welcome to the first Team Unsinkable sprint recap! We have been extremely excited to complete our first sprint since we started using Agile Scrum and it has finally happened! By far the most exciting development this sprint has been our software team's work on TensorFlow object detection.

Software Updates

It is pretty obvious that our first model didn't train too well. We have had success in the past with TensorFlow 1.14 but TensorFlow 2 doesn't seem to want to play ball. It's been pretty difficult trying to implement TF 2 given how little experience our software members have with it compared to version 1. Regardless, Tim has been making extremely good progress towards getting our custom model detecting properly. One test we did to make sure that the fault was with our model as opposed to our detection script or any other factors was to run a pre-trained model that we know works properly. By attempting to run this model, we would be able to see exactly where the problem lies.

He's a little confused, but he's got the spirit!

This test proved that our detection script has been working properly and that we have some issues to work out with our model. One of the most exciting achievements with this test was that we were able to obtain the bounding box data that was hidden deep within all the scripts that TensorFlow uses. With this bounding box data, our team working on ROS can begin to work on sending the data over to our controls software.

Speaking of ROS, our ROS team has been working diligently on getting MAVROS and ROS installed on all of our main computers. With everything set up properly, their next task is to begin to send the bounding box data from our NVIDIA Jetson TX2 running our detection script over to our main onboard computer, an Intel NUC, and our Pixhawk PX4 autopilot. The hope is to be able to get some basic following behavior working before our next testing day.

Electrical and Mechanical

Mechanical has been getting a lot of work done on developing the torpedo and launcher, arm, and dropper mechanisms for Nautilus. With most of these components being designed in CAD, prototyping utilizing FDM 3D printing has begun. Once the size and position of these components have been tested and found to be acceptable, parts will be ordered and the final mechanisms will be manufactured.

3D printed prototype of the emergency stop assembly. The assembly will hold a reed switch which will be connected to a relay within the enclosure that will control the emergency stop.

The mechanical team has also been working alongside the electrical team in order to figure out an efficient layout for all of the internal electronics in order to be easy to work on and capable of being cooled using tiny fans within the enclosure. Once a proper footprint has been determined, the electrical team will begin the final PCB layout of their long-awaited custom power distribution board. The electrical team has been extremely hard at work designing the power board and we cannot wait until we get to hold it in our hands for the very first time.

Preliminary render of the back enclosure tube with the expected power board footprint.

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