Posted by Trygve Thursday, July 19 2007 18:25:35
Posted by Trygve Friday, January 19 2007 20:18:45
The battery is a Hyperion 3S 20-30C 800mAh, and when I put it on the scales I got a nice surprise. It only weighed 68grams - 70 with the connector from the old battery - so I'm shaving 13 grams off of the total weight of the X-UFO. That, and I'm doubling the power... That translates into FLIGHT TIME!
I got the battery and charger from Elefun.no, a Norwegian shop, but most well-stocked R/C-hobby stores, particularly those catering to 'electric-flight' enthusiasts, have them in stock.
Posted by Trygve Friday, January 19 2007 00:26:57
That was the good news...
The not so good news is that the distributor screwed up and sent me 0603-size SMT 100KOhm resistors, when I had ordered 0805-size.
The difference? 0805 is a pain to work with, and the 0603 is even smaller...
I'll still try to use them, though(so that I can test the ADC setup, and get some data out of the Gyro and stuff), but I'll also order a new set. Besides, I still need to order a few other components, like MOSFETs, Xtals, possibly a couple of EEPROMs, and I really should try to find a 3.3V compatible digital compass circuit.
Posted by Trygve Wednesday, 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.
Posted by Trygve Tuesday, January 16 2007 20:27:40
Got the gyro/accelerometer today.As I already have a few Propeller chips(SIP40 modules, but OK for testing), all I need now is a few resistors and capacitors.
They are on order from a local supplier as Sparkfun doesn't seem to sell 0805-size SMT components.(They're a pain to solder but it's necessary to shorten signal paths. The recommendation is 0603-size components, but as I'm not that much of an masochist...)
Until they arrive, I'll just occupy my time doodling PCBs...
Posted by Trygve Tuesday, 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.