Wednesday, August 17, 2016

Q3 2016 Rocket active stabilization system update, complete hardware redesign of fin drive system with bonus sketches and a needed disclaimer

The old and new designs, massive improvements to the overall design
Update time has rolled around again now that a good chunk of progress is completed on the Arduino based rocket stabilization system. This has taken a while since I've been busy with not only work but also getting the A+ certification in computer repair and completely reworking my current workstation. After much discussion with several other rocket tinkerers, the conclusion was reached that stresses on the servo spline itself would be quite considerable and may result in damage or inoperability. Based on force distribution I surmised that flanged bearings embedded in the system shroud tube would function as not only supports but also as smooth rotation points. With the challenge of a new fin drive train in mind, I set to brainstorming. My first thought was to use linkages connecting the servo to the actuation shaft, though it would increase the diameter of the system unless the servos were staggered which would also increase the overall height of the system. Stepper motors were considered, however as I was unable to find suitably sized units and the common 28byj-48 had too low precision and torque this too was eliminated from consideration. After those two ideas were discarded, it was relegated to the back burner while I had work. The breakthrough was about a week later, while browsing patents looking at missile fin drives I noticed an old Raytheon control segment used bevel gears to transfer the motion and that became the seed for the new design. 

Tuesday, June 14, 2016

Side projects update: Optical/radio telescopes, CAD, new rigs and custom sensor breakouts

Apologies for the radio silence on this blog, work has been continually crazy and some projects have been sidelined for temporary holds due to funding reallocation, however the backlog of completed short term projects has been full for a while and I thought I'd get some posted to tide you over until the next flagship update (Coming soon! Major redesign underway). Details on projects after the break, with a teaser for the flagship redesign at the end. 
8 inch Dobsonian telescope with craptastic eyepiece

Friday, March 11, 2016

How to theme and change the font of the Arduino IDE (Tutorial)

You've probably had this problem before; Writing code late at night trying to get new features to work but the bright white of the default IDE is burning your eyes and giving you a headache even with F.Lux installed, and/or you've mistaken a "l" for a "1". Well, there are solutions to those problems, but not the other well known problems (autocomplete, not enough debugging features, etc etc) after the break.
Original on left, rethemed and refonted on right

Sunday, February 14, 2016

Q1 2016 Rocket active stabilization system update, now with fins, nose cone and a mockup

With 2016 well underway it's time for the first update on the state of the stabilization system!
First off, apologies for the massive delays this post has had, was originally slated for mid-Jan launch but between job hunting and other stuff I've been hitting delays and trouble at every turn. Since last semester ended on Dec 18th, I'd been going to TechShop pretty much every day until Jan 18th making massive leaps and bounds of progress along the way. The most obvious of progress is the completion of the demonstration mockup airframe which will be gone into more in-depth after the break. 
The system's current state on the demonstration mockup

Thursday, January 14, 2016

Holiday update and gift exchange postmortem

Happy Hackerdays readers! Since the last update it's been busy with the first semester of school finishing up, finals and the holiday season quickly approaching. In that time I've made a better HackerTree, run a beta test of the Maker gift exchange, made the major purchase of an oscilloscope,  and received a box of goodies from Texas Instruments. First semester was a mess and I made a lot of mistakes along the way that will be a lot of work to get my grades up out of over the rest of my time at school. I've reactivated my TechShop membership and will be up there doing a lot of work until January 17th when it expires again. Full details on the updates and a little teaser of the stabilization system progress after the break.
Wishng you all a maker Christmas and a hacker new year!

Wednesday, November 18, 2015

Rocket active stabilization system debugging update

Debugging the system on a cheap logic analyzer clone (review coming up soon)
        Ever since I implemented the new control code this system has been plagued with a pair of bugs that frustrated me to no end which I have dubbed "Harlem Shake" and "Mr Freeze." The "Harlem Shake" bug occurs when the IMU outputs seemingly random YPR values suggesting that it is tumbling even when the sensor is kept perfectly still. "Mr Freeze" as the name suggests, is when the system locks up out of nowhere and refuses to respond unless reset which does not prevent the glitch manifesting. After mucking around with the code and a string of long nights with quite a bit of coffee trying to figure out what the heck was wrong with the system, I finally fixed the problem. The following is just inferences based on my limited knowledge at the moment, if anyone has a better theory I'd be glad to hear it. Reading the serial logs led me to believe that the freezing glitch was caused by a FIFO (First In First Out) overflow due to the appearance of that message in the terminal just before the system locked up. Initially, I had messed with the FIFO data speed configuration from 200Khz to 400Khz to no avail before inferring that the data was coming in at a much higher rate than it was being output, being a problem in library implementation. Using a logic analyzer had not showed anything anomalous in the I2C data bus which would have signaled a problem with either the wiring or packet structure. My assumption is that the transcoding of the data  internally was taking up too much processor power or was out of sync causing it to glitch thus causing the system to grind to a halt. This is a library-level issue that I'll be investigating and attempting to fix. Googling around proved library wonkiness to be the case and the fix was to increase the baudrate to the maximum of 115200. After applying this single line fix, the system ran for 10 hours straight without any bugs or freezing at all. I have no clue as to what causes the "Harlem Shake" glitch but it has not appeared since the freezing fix was applied so I'm not going to complain, though it has me curious as to what the core of the problem is.

Thursday, September 17, 2015

Hackaday DC event recap

Giving a talk to the packed room
As some of you might have seen, I recently attended the Hackaday DC event and gave a talk on the rocket stabilization system while there in addition to explanations and demonstrations to quite a few people that came by my table. Surprisingly, the Amazon AWS crew that was there took quite an interest in my project and gave advice on code upgrades for the stabilization system, namely dynamic control movement ranges dependent on velocity.