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About the Project

One day, while surfing the net, I happened upon a cool RC-toy...
Of course, I couldn't control it, so there was only one thing to do...
Modify the Heck out of it!

Weighing in.

Techfiles Posted on %PM, January 17 2007 23:16:34

Found a decent scale today, so I measuered some weights.

The X-UFO, complete with batteries, is 320 grams.
Battery is 83 grams,
The Gyro is 16 grams,
and the Transparent dome is 5 grams(with the doublesided tape that held it in place.

I found a replacement 11.1V/800mAh Li-poly pack at approximately the same weight in a netshop, so I won’t save any there. (I could have gone for a 400mA pack, at about 40 grams, but then I would still be struggling with a 4minute fligh-time. Which really isn’t long enough when testing stuff)

The replacement gyro is 2 grams, so a theoretical saving of about 5% of the total weight.

As I won’t have a RC receiver built into the electronics, I may be able to save a few grams there, too.(Any saving depends on how good I’m at designing double-sided PCBs with surface-mount components.)
I know that I won’t be needing all the connectors that the original PCB had, but that saving will be minimal.

In the beginning…

Techfiles Posted on %PM, January 16 2007 20:02:32

In the fall 2006 I happened upon the Silverlit X-UFO, and immediately knew that I had to have it…
And just before Xmas I had it in hand.. .

A short description is: a Radio-controlled flying device using 4 small motors driving one propeller each. Two are rotating clockwise, and two anti-clockwise.
All the motors are independently controlled by an onboard microcontroller, and stability is supposedly achieved by a mechanical gyro located on top of the device.
Power is with an 80gram 12V/350mA Ni-mh battery pack, and it has about 50grams cargo-capacity.

A quick test showed that I didn’t have a snowball’s chance in hell to control it, gyro-stabilized or not…
Of course, THAT just made me more determined, and I decided to rebuild and modify the heck out of it.

The microcontroller is just a ‘blob’ on the main PCB, and the gyro is a big mechanical ‘whirlygig’ which can only handle tilts up to 20°, seriously impacts the cargo-capacity and probably drinks power as if it is going out of vogue soon. (Not that the 350mA pack can deliver more than 4 – 5 minutes of air-time, anyway) So, time to kit it out a bit…

The new microcontroller will of course be the Parallax Propeller(QFP package).
For the uninitiated, that is an 8core 32bit microcontroller capable of running from 20KHz to 80MHz, so it should have the raw power needed. It can also be programmed in both assembly and a high-level language(called Spin).
The fact that a single COG(that’s what the cores are called) can do 2 Analog-to-digital conversions at the same time didn’t hurt, either. (No it doesn’t have dedicated AD circuitry.)
By multiplexing the AD conversions, I should be able to do as many as 12 or more conversions from one COG and still get more than 100updates/second for all of the inputs. (not even fighter jets have more updates to their control surfaces more often than that… )

The Gyro is as noted, an ugly blob of spinning parts and moulded plastic, supposedly giving X/Y-axis as analog outputs. I figured that the IMU 5 Degrees of Freedom electronic X/Y gyro and X/Y/Z accellerometer, would do the task just as well.The fact that it also runs on 3.3V, just as the Propeller, doesn’t hurt, either.
That will take from 2 to 5 AD inputs as I learn to use it and starts implementing the control system.
No, the original X-UFO design doesn’t have an accellereometer. (It doesn’t hurt that it weighs in at about 2grams, either)

To avoid bumping into things or ‘landing it’ unintentionally, I’ll also add a couple of IR proximity detectors around the edge and on the bottom. These will also use AD inputs, which explains my need for a lot of AD conversion capacity.