Henry Fletcher's Blog (9)

Switching from DCM to Quaternion

We've recently made the move from the old clunky DCM implementation to a new Quaternion approach, and it seems to perform better, or at least the code is much smaller and takes almost no time at all to execute on our 72MHz 32-bit flight controller. I'll be writing an article on the Quaternion method as part of our series on Engineering Insights.

We've also added MAVLink support, and full integration with QGroundControl GCS.  This helps greatly with debugging, and of course enables…


Added by Henry Fletcher on January 6, 2012 at 9:24am — 35 Comments

'Engineering Insights - Lesson 2: Testing and Tuning Always takes Ages!

Video of ROFL Tuning Session with spectacular crash when we deliberately detune one of the PID values! No quadcopters harmed (much) in the making of this video.  Video of stable flight below.

By the way, the ROFL quadcopter kit is still on sale on my website:…


Added by Henry Fletcher on December 27, 2011 at 8:00am — 3 Comments

Engineering Insights - Lesson 1: Problems with Prototypes!

Seraphim is our sensor board for the quadcopter, it includes accelerometer, gyroscope, magnetometer, barometer, GPS and micro-SD card slot.  With the exception of the GPS unit, all of these components are a complete pain in the backside to solder properly, and there are some consequences of not…


Added by Henry Fletcher on December 10, 2011 at 6:30pm — 5 Comments

UAir: Integrated Wireless Comms - Making life soo much easier!

Here you can see the little guy we have just begun to use and will be releasing for sale in early October. The black Forebrain board is what was running the autopilot code in ROFL up till now, 72MHz ARM Cortex-M3 microcontroller, measures 66mm*23mm.  The longer Hivebrain board is what we will switch to and will…


Added by Henry Fletcher on September 11, 2011 at 3:03pm — 3 Comments

Latest news from the chaps at UAir: ROFL Flies at Night...and erm... crashes!

Well, after a rather merry holiday in Scotland I'm back and will be posting a load of development videos (mainly of ROFL) for those that are interested. This is our first attempt at flying outdoors in the night. Actually this is the first time I have ever tried to fly a model outdoors at night, it takes a little getting used to, all your old reference…


Added by Henry Fletcher on September 11, 2011 at 7:31am — 2 Comments

Whooops a Dasiy! and Trying to Destroy a ROFL Frame

As with any inventor, designer or engineer, things don't always go my way!


Actually as it turns out, I did not damage the Seraphim prototype, but did destroy the reciever! That cheered me up a bit as we have much more need for the Seraphim rather than the reciever at the moment, I have spare of the latter.

Nonetheless, the lesson…


Added by Henry Fletcher on August 19, 2011 at 3:17am — 2 Comments

Shocked myself! Talon Flies!

So, a month or so ago I told people about the crazy Talon airframe I had built and wanted to try and fly:


Well, now I have it flying!!

I have written a…


Added by Henry Fletcher on August 13, 2011 at 1:00pm — 8 Comments

ROFL Flies!

More information on all the projects I'm working on can be found at my website: www.universalair.co.uk

As you may or may not remember I hadn't got my crazy experimental airframe flying (Talon:…


Added by Henry Fletcher on August 11, 2011 at 4:11pm — 5 Comments

DIY/ Engineering Excitement over the past few months!

When I first got interested in UAVs I took the advice of some of the forum members here and equipped myself with arduino based systems....but I'm a crazy engineer and this approach didn't last long before I had convinced myself I could make a better job of all this if I started from scratch...luckily I also managed…


Added by Henry Fletcher on July 23, 2011 at 1:00pm — 5 Comments

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