Project Absolution Weekly Review Live Later Today! (Patreon)

Hey folks! Today is a real-job work day for Charlie, so the stream is later in the evening, sorry! As always, it will remain up and you're free to watch it later if you'd like!

I like the idea of doing a TLDR for those who don't have time for a whole stream, so here's my week!

All of the core inter-processor comms stuff for AVA is complete, and it's really solid. I'm using I2C between each processor, and messages are sent back and forth in 28 byte packets with a 4 byte checksum at the end. Each subcontroller also has a vigilant watchdog timer on these comms. If it doesn't hear from one of the other processors in a certain number of comm cycles, it can call yell real loud and call an abort. There are lots of ways you could set something like this up, but so far this method works like a charm and I feel good about it.

All of the "where am I????" code is moving right along. I've got reliable readings from the GNSS radio, good performance on the IMUs, and coming up this week is work on sensor fusion. I'll be building out a nice Kalman or Extended Kalman filter to get high precision velocity and position estimates. I can get like 5hz pos/vel estimates out of the GNSS, but by incorporating the rest of the inertial navigation sensors, ANNNND building the KF around the actual state-space vehicle model, we can get a filter that converges very quickly and accurately. 

I've got the state machine set up and working well, that's the thing that helps AVA move through isolated sections of code. It looks for cues like liftoff, burnout, apogee, etc. Many of these little functions and subroutines come directly from Signal R2 and Sprite's codebase, which REALLY speeds up development! I anticipate we'll be able fly AVA on Sprint in maybe two weeks? This is one of those things where it perpetually feels like it's two weeks out until one day it's not... 

You may have noticed that AVA has active fin outputs as well. This may end up being helpful for Absolution with grid fins, BUT it will also be helpful for a different project(because I have a serious problem with doing many projects at once), which I'll call, Tropolaunch... :)

Blue skies, and see you at the stream! If you can't make the stream and have questions, leave them in the comments here and I'll get back to you!

Joe