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RHTizzy's blog
Archive for September, 2012
Posted by RHTizzy | Sep 18, 2012 @ 02:07 PM | 3,170 Views
Got the following from RC Timer for use with the x650 and the Crius AIOP
Gimbal
Servo's



At the moment I'm struggling a bit to get it going, all it does for now is resist movement instead of adjusting to movement... iow, the gimbal servo's are not controlled by the controller on roll or pitch but instead hold position and try to hold center position.

What have I done so far?
- connected servo's to CAIOP pins 44 & 45 Roll & Pitch (no free channels for using pin 46 Trigger, so might have to disconnect something else)
- connected Rx to ch7 & ch8
- defined SERVO_MIX_TILT in config.h
- I'd removed all red leads from the ESC's but it turns out that 1 needs to be connected to power the servo's

Time to google
Posted by RHTizzy | Sep 15, 2012 @ 05:14 AM | 2,644 Views
I found the seemingly best post on tuning PID's so far:
http://www.rcgroups.com/forums/showthread.php?t=1375728

After all I've read, I liken PID tuning to driving a car with a somewhat loose steeringwheel and wanting to change lanes: how much force to apply (P) to the steering wheel for how long (I) and how quickly (D) you need to make adjustments is basically what's needed to change lanes as smoothly as possible...

Tuning in short (much thanks to Shikra):

For Aerobatic flying:
Increase value for P until oscillations start, then back of slightly
Change value for I until until hover drift is unacceptable, then increase slightly
Increase value for D (remember, that means a LOWER number as it is a negative value - i.e. closer to zero) until recovery from dramatic control changes results in unacceptable recovery oscillations
P may now have to be reduced slightly

For stable flying (RC):
Increase value for P until oscillations start, then back of slightly
Change value for I until recovery from deviations is unacceptable, then increase slightly
Decrease value for D (remember, that means a HIGHER number as it is a negative value - i.e. further from zero) until recovery from dramatic control changes becomes too slow. Then Increase D slightly (remember - lower number!)
P may now have to be reduced slightly


For stable flying ( AP / FPV):
Increase value for P until oscillations start, then back of slightly
Change value for I until recovery from deviations is unacceptable, then increase slightly
Decrease value for D (remember, that means a HIGHER number as it is a negative value - i.e. further from zero) until recovery from dramatic control changes becomes too slow. Then Increase D slightly (remember - lower number!)
P may now have to be reduced slightly

You will have to accept a compromise of optimal settings for stable hover and your typical mode of flying. Obviously factor it towards your most common style.
Posted by RHTizzy | Sep 10, 2012 @ 06:14 AM | 3,240 Views
As the RM450 was rather rudimentary I decided to use the experience to go one up and get a folding frame from RCTimer. Still using the parts I had from the previous build, so Crius All In One Pro with 1045 props, 30A ESC's and 2215 930Kv motors. It's almost double the weight though so have ordered a pair of 2450mAh 30C's from Hobbyking which should provide plenty of lift and connected in parallel provide plenty of flight time..

Here's the build log


...Continue Reading
Posted by RHTizzy | Sep 03, 2012 @ 08:14 AM | 2,604 Views
Got my 3rd flight in today and can happily share that the quad flies! It appears though that the 2200 15c batteries are indeed way underpowered for the job and within a minute or two the quad starts showing an ever increasing height oscillation and has trouble staying up on roll or pitch. Within 3 or 4 minutes it's reduced to a hopper that can hardly clear the ground.

I still had a few 1300mAh batteries from my ARdrone times which are 30C and they actually last longer and give more power (ie better throttle response) than the 2200's! Connecting 2 actually gives almost 5 minutes of actual control but obviously the quad needs tuning and control is perhaps too big a word. In fact, without level, mag and baro active it's almost impossible not to crash as the quad is extremely sensitive to the controls and has a tendency to rocket off in whatever direction I twitch the sticks. But with these power problems there's no point in trying to tune anything so I'll be waiting for my replacement 2450 30c's before I can get started with any serious flying.

About the batteries, I went for the smallest size and weight which I thought would have enough juice to sustain at least 60% of max amps for a few minutes, but I'm thinking maybe I should order some bigger ones. Tricky though as bigger also means heavier, any recommendations?

Anyways, I've locktite'd the motors and frame so that should be fine for a while. How do I get them loose though, is it enough to put some heat on it with a heat gun?
Posted by RHTizzy | Sep 01, 2012 @ 07:14 AM | 2,659 Views
Went out for the first actual flight this morning since the very short test day before yesterday and actually I'm a happy chappy even though both first and second flight ended in disaster.

I take off too close to the edge of the clearing and 30sec into the first flight it gets into some trees, crashes to the ground and brakes a leg right at the landing joint.
Good thing? It hit the tree about 10meters up, so that's a major improvement as far as the hopping goes

Second flight I learn from the first and take it to the middle of the field. There's quite a bit of wind and it takes a few tries before I get the hang of hovering at a certain height. As the minutes (which feel like seconds) go by it gets harder to control and the end of it is a hard landing whereby one of the motors comes right off. Closer inspection shows all the screws have gone. Probably due to vibrations and lack of locktite
Good thing? I got to see it working properly and even switched from acro to level to baro to mag. And could see the result of each!

Okay so it resonated up and down a bit but it did so keeping itself pointed in the right direction and pretty much level. I didn't get to try RTH out but was happy to see the GPS unit got a fix in seconds!

Done flying for now and won't have time for a few days either but in all honesty, all in all, I'm a happy happy chappy!

Oh yes, I used Q-bond to fix the broken leg and boy is that the best buy ever!