Featherweight Blue Raven Development Thread: Deployment logic

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Hey Adrian! Does it look as if you may have any available around May? Looking to bust the H record again, and then I'm going to start doing staging activities as well. Would love to have a Raven for that! If not, I'll take a gander on the classifieds for a Raven 4 :)
 
This is the first in a series of development threads in which I'll discuss some design features and tradeoffs of the upcoming Blue Raven altimeter, and give everyone a chance to provide feedback. I'm going to break up the development thread into topics so it will be easier to navigate as the discussion evolves in the future. Disclaimer: This is a behind-the-scenes look that will discuss features that are likely going to change before the final product, and some of which may need to be abandoned or put off.

Background:
The Blue Raven is a ground-up redesign of the popular Featherweight Raven altimeter, built around a much more powerful microcontroller that has Bluetooth capability. The Blue Raven keeps the same small form factor of the Raven, meaning it will fit in 24mm rockets on up, and it will be compatible with all existing Raven av-bay accessories. I'm investing in a top-quality phone app (Apple and Android) to handle all user interfaces for the Blue Raven, including live data, deployment configuration, data download and graphing, etc. Flight testing will take place this spring and summer, and my goal is to have the Blue Raven available for sale early this fall, for about the same price as the current Raven.

Today's topic is the deployment logic. Similar to the Raven, the Blue Raven has 4 output channels. The Raven is very limited in code space and hamstrung by some early design decisions I made, which meant that the 4 output channels had so share some flight event criteria. Below is the setup screen for the default settings all 4 Raven deployment channels. For example, any of the deployment channels had to use the same value for the velocity threshold Vel1 (400 feet/sec in this case):

View attachment 513527

For the Blue Raven, there is enough memory to let each channel have its own independent thresholds. The Blue Raven will also feature full 6-axis inertial sensing (including gyros) and integration that will provide more options and fault tolerance for deployment than were possible before. Here's what I currently have for the flight events that can go into decision to fire a deployment channel. Keep in mind that while all this flexibility is possible, I'll design the user interface to have good default settings so that someone can just buy-and-fly with confidence, and also provide common setups to select from so that nobody is going to have to make a million choices and enter a whole bunch of parameters unless they want to do something really off-the-wall Each all-cap abbreviated word in bold is a threshold that can be set by the user.
  • Barometric altitude above the pad < AGL1
  • Barometric Altitude above the pad < AGL2
  • Flight angle < FANG1
  • Flight angle > FANG2
  • Time since liftoff < TVAL1
  • Time since liftoff > TVAL2
  • Accel-based total velocity < VEL1
  • Accel-based total velocity < VEL2
  • Barometric pressure increasing
  • Barometric-derived upward velocity < BVEL (negative number during descent)
  • Fault-tolerant apogee detected (Two of three sensors indicate apogee: accel-derived vertical velocity < 0, baro pressure increasing, gyro flight angle > 90 degrees)
  • Motor burnout counter > BURNCOUNT
  • 1 second since Apogee channel fired
  • 1 second since Main channel fired
  • 1 second since 3rd channel fired
  • 1 second since 4th channel fired
When all the selected events are true, then the output fires. These set of flight events also opens up the potential for having a set of backup criteria for each channel. For example, the main chute channel can fire with the primary criteria being:
  • Fault tolerant apogee detection took place
  • Barometric altitude above the pad < 700 feet
  • Motor burnout counter >= 1
and then also have backup criteria to fire the main chute:
  • Fault tolerant apogee detection took place
  • 1 second since Apogee channel fired (avoids getting spoofed by pressure spike if the av-bay isn't well sealed)
  • 1 second since 3rd channel fired (3rd channel default would be apogee backup)
  • Barometric-derived upward velocity < -150 feet/second
  • Accel-based total velocity < -150 feet/second
This way, if an apogee charge is undersized or a dud, the main will have a chance to come out before the rocket falls fast enough to shred. I'm currently thinking of making the backup criteria for the main chute part of the default settings. The trick will be to make this easy to understand and use.

Comments are welcome.
Any update on how soon I'll be able to place an order for a Blue Raven? In time for our currently under construction rocket to use in April, 2023?
 
Thanks for your support and interest, everyone. I took the first round of beta test units to the post office yesterday, after using new automated testing for the analog measurements and outputs. I still have some work to go before the production programming, calibration and testing can run completely unattended, but the core pieces of that capability are working.

Next up is adding the Bluetooth user interface. The user interface design has been through a couple of iterations in a UI design tool, so my phone app developer is starting to code those screens into the app. The link between those UI features and the Blue Raven hardware is defined by Bluetooth services. The app developer and I need to define those and write software on both sides to add them. I haven’t done this before but I’m guessing it will be 4-6 weeks to get the basic functionality that every user will need to use it with phones. (see previous forum page). My software development time estimates have been consistently optimistic though.
 
A status update: The Blue Raven's Bluetooth phone interface is making progress every day. Here are the phone interface features currently working:
  • Bluetooth advertising and connections
  • User-settable device name that's used throughout the application
  • Over-the-air firmware updates
  • Phone automatically sets the date and time on the Blue Raven
  • Live data display, including continuity voltages, 9 axis sensor data and health, armed/disarmed status, battery voltage, temperature
  • Arming and disarming each of the 4 output channels
  • Enabling/disabling the beeper
  • Multi-unit support
Additional minimum features that need to work and be tested before the Blue Raven goes on sale:
  • Configure the deployment settings
  • Simulation setup, start and stop
  • Automatic download of flight summary data
The configuration and simulation features are pretty far along. The next features to get added after the Blue Ravens go on sale are:
  • Download of low-rate and high-rate time history data
  • Graphing of recorded time history data
  • Log of every flight
  • Sharing flight data
  • Storing and sharing deployment configuration setups
Beta testing has been underway for a few weeks but no beta testers have flown their units yet as far as I know. I did my own Alpha test flight on Sunday and uncovered a problem with the apogee detection algorithm that I have since fixed. My next test flights will be on the 18th. I'd like to have all the essential Bluetooth features working by then for me and others to test out.
 
All of the minimum phone app features are now at least partially working, and I think they will be in decent shape after a few more iterations, probably next week.

My focus now is on getting ready for more flight tests on Saturday, and then finishing my production programming and test fixture software, which has been taking a lot more time than I had expected.

I need to design some quick-start cards to include in the production boxes and get those printed. If my beta testers will fly their units in the next couple of weeks, I think we could still be on track for a release by the end of the month if there aren't any big surprises.

On Saturday I'm planning to fly my little minimum-diameter 29mm rocket on a G80, and if that goes well, fly again on a CTI I243 for a supersonic flight over 11,000 feet.
 
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Today I'm working on my inertial sensor calibration fixture.
WOW! That is really cool! Pardon me if this is something that everybody already knows but what is that "erector set" material called and where does one get it?
 
I'm happy to say that the phone app is now in a usable state for all key features, including:
  • Modifying the deployment logic settings, and resetting the deployments to default values
  • Showing live data for checking ready for launch (continuity voltages, channel armed state, sensor health)
  • Running a flight simulation that verifies the deployment settings
  • Auto-download of flight summary information (max altitude, max velocity, and dozens of other metrics) after the flight
  • Naming the Blue Raven
  • Disabling and enabling beeps
  • Switching between multiple Blue Ravens
  • Arming and disarming channels
  • Flight log of all simulated and actual flights, with one click to more detailed flight data
There are still some minor known bugs and the testing of the deployment logic settings is still in early stages. And for now, in order to download the time-history data, calibrate the accelerometer or manually test-fire charges, you can only do that through the USB interface. I'll be working on those features next. but in the meantime,
I'm expecting to get some Beta tester results from flights this weekend. Over the next week I will be calibrating and testing units, and working to fix minor bugs. I'll hopefully have 2 days to put up a bunch of test flights of my own at NCR on April 1-2, and then I'm expecting to ship the following week.
 
I'm happy to say that the phone app is now in a usable state for all key features, including:
  • Modifying the deployment logic settings, and resetting the deployments to default values
  • Showing live data for checking ready for launch (continuity voltages, channel armed state, sensor health)
  • Running a flight simulation that verifies the deployment settings
  • Auto-download of flight summary information (max altitude, max velocity, and dozens of other metrics) after the flight
  • Naming the Blue Raven
  • Disabling and enabling beeps
  • Switching between multiple Blue Ravens
  • Arming and disarming channels
  • Flight log of all simulated and actual flights, with one click to more detailed flight data
There are still some minor known bugs and the testing of the deployment logic settings is still in early stages. And for now, in order to download the time-history data, calibrate the accelerometer or manually test-fire charges, you can only do that through the USB interface. I'll be working on those features next. but in the meantime,
I'm expecting to get some Beta tester results from flights this weekend. Over the next week I will be calibrating and testing units, and working to fix minor bugs. I'll hopefully have 2 days to put up a bunch of test flights of my own at NCR on April 1-2, and then I'm expecting to ship the following week.
Not yet seeing a pre-order option (did I miss it?). I'm guessing you're working on that in the website as we speak?
 
Hi there,

Does the Raven Blue have Tilt inhibition (For a Sustainer stage)?
And can it be remotely armed?

Thanks!
 
Tried to pre-order, but got stuck right after entering address on the order page - firefox on linux. Oh well. Probably just me.

Gerald
 
Thanks. I’m up to 73.

Lots of little things in the app are getting ironed out. After a lot of focused work, my production test and calibration setup is ready to try out for the pre-orders.

Releasing the app through the Apple Store and Google play are in work.
At this point if I ordered one would it be delayed from the initial ship date?
 
At this point if I ordered one would it be delayed from the initial ship date?
Not beyond a day or two that it will take to just fill all of those orders. I have plenty of hardware stock for now. I don't know what my max throughput is for programming and testing boards with my new production setup, but next week I'll find out. Probably 50-100 units per day. Packaging and shipping orders may be a bit slower than that.
 
A status update:

I had a good test flight on Saturday with an I243 in my 29mm dual-Blue Raven test rocket to 13,170 feet, Mach 1.6. The Blue Raven deployments worked without any surprises and the data from both Blue Ravens look good. Unfortunately, I broke the shock cord to my aft section so I'll need to rebuild for future flights. But as far as the Blue Raven is concerned there wasn't anything that will keep me from shipping the pre-orders this week. So Karen and I got started with that today:
IMG-0769.jpg

20 Blue Ravens out, and 87 to go. Meanwhile I'm still finding and fixing hiccups in my production programming and test fixture that are slowing down production. Also meanwhile my app developer and I are still making daily progress on new features and bug fixes. It's busy, but a good kind of busy.
 
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