Virtuall flybar for AP applications?

[askman]

sounds like a cool gyro and project.


I have a question. I've seen several dual axis tilt sensors with accuracy of sub 1 degree with range of 60/-60 degree in the market. I would think it would make excellent heli levelling sensor. may be cost prohibitive right now, but probably not for long?

[Angelos]

Askman,
There is not major difference between the tilt sensors that I have seen and accelerometers. They are accelerometers in effect but they perform the cosine calculation on the sensor and give you a linear signal proportional to angle. However they are still susceptible to dynamic accelerations and thus they will also pick the movement of the helicopter, not just its angle.

-Angelos

[MarkWebber]

Here's how it looks so far. Don't pick apart the wiring. I'm waiting for a crimp tool and connector ends to show up.

I really like the look of the head w/o a flybar.

[MarkWebber]

Duplicate

[GGoodrum]

Mark, I love the head too, very simple!

Ugh, we need to get you electrified as well...


Angelos, this new little widget is very cool, but it now begs the question, can you combine this with the AP-2000i, or maybe an appreviated version with just the eCCPM mixer to do a V-Stab competitor? Also, will you use some form of this for the inertial sensor for the AP-2000i?

-- Gary

[Tonystott]

I can just see it now... Angelos releases the ultimate black box:- incorporating virtual fly-bar, head holding tail servo, flight stabilisation and altitude holding!

and it might not be so far-fetched at all

[GGoodrum]

Originally Posted by Tonystott

I can just see it now... Angelos releases the ultimate black box:- incorporating virtual fly-bar, head holding tail servo, flight stabilisation and altitude holding!

and it might not be so far-fetched at all

Yep, that's where I was going as well!

[Angelos]

Angelos, this new little widget is very cool, but it now begs the question, can you combine this with the AP-2000i, or maybe an appreviated version with just the eCCPM mixer to do a V-Stab competitor? Smile Also, will you use some form of this for the inertial sensor for the AP-2000i?

This is definitely where this is heading. Also, I have made some provisions to use the gyro for a variety of other tasks which will be very interesting to the AP operators.

I can just see it now... Angelos releases the ultimate black box:- incorporating virtual fly-bar, head holding tail servo, flight stabilisation and altitude holding!

The ultimate RC black box is probably a natural evolution in the industry like other markets. Take mobile phones for example… they now come with mp3 player, digital camera etc. However in this hobby people like pick and match the best gyro with the best governor and the best flybar-less mixer. To be successful we need to be the ones who combine the best devices on the same box. So far I feel we have done a great job with the AP-2000i and the gyro will be no exception.

The possibility of interconnecting stand alone devices is also very interesting. For example the gyro has a communications port and when we develop a governor it will also have one. Thus the two devices can exchange information between them. The gyro can inform the governor when extra engine power will be needed for the tail rotor and the governor inform the gyro about changes in throttle (from TX curve or locally computed) which would result to changes in torque. So the gyro will be ready to compensate for these.

-Angelos

[MarkWebber]

Ugh, we need to get you electrified as well...

That's where I think I'm heading. Bergen E-Magnum, I should think...are you listening, Chris? :wink:

Besides, what better heli to chop up to try things out than my rappy?

[oscillator]

Hey Angelos,

for those of us playing with flybarless AP rigs now, what gyros would you recommend for pitch and roll? Of couse I'd love to use your gyros/black box if you want to send me some. :mrgreen: Oh, and get those AP2000i's in the mail to Webber so he can send me mine. :wink:

Mark Webber,

any more test flights after reducing the mechanical "gain"? I've seen some people keep the washout block and arms as a further mechanical reduction from the swash to the blades. Not as clean as reducing the servo arms, but if the inner hole is still too much gain it might be worth a try.

[MarkWebber]

Mark

I was hoping that I'd get a chance to try out the mechanical reduction today. Won't quit raining, though. I feel good about it. After making the change yesterday, motion test yielded much more subtle gyro inputs. I think that will turn out to be the answer. I wish I'd have made that change prior to gyro adjustments. I'm sure I'll need to reset the gyros now.

If the weather will just improve now then I can get to dialing this in. I'm itching to fly it with the IR installed. Should be sweet!

[Angelos]

Mark (oscillator),
It is recommended that you use Normal (rate mode) gyros. In which case it does not matter which gyro you decide to use the rate mode does not suffer from drift. However, because the cyclic signals pass through the gyro I recommend that you get decent quality gyros. Some of the cheap gyros have very low resolution and you may loose the nice “feel” of the cyclic. The 401s that Mark Webber picked are probably a good choice. Let’s wait and see how get gets on.

-Angelos

[MarkWebber]

Got to get in another test flight today. A bit windy and only 25F but I couldn't help myself.

It's much better having moved the ail and ele servo links to the inner servo arm hole. No oscillations at all. I'm thinking it might even be able to stand a bit more gain and less delay. It was a bit pitchy in fff. Gain on ele gyro, probably?

Anyhow, it's back to flying more like preconversion R50. Except the roll/flip rates are ridiculious. There does seem to be some roll/pitch coupling. Maybe rotor phasing needs tweeking. Hard to say because I was shaking from the cold.

I need a nice day and little assistance to get it dialed in right. Even so, it's still flying pretty well.

[GGoodrum]

25F?? Man, you're dedicated! I won't even go out to the car if dips down to the low 50s...

[MarkWebber]

I hear ya, Gary. I was born in Anaheim and lived on SoCal for most of my childhood. I suppose one gets used to it

[oscillator]

Thanks for the update Mark. I was wondering earlier today if you had made any progress. Thanks for braving the cold for the cause!

Are you using the digital setting on your 401's? Would it make any difference in this application? I was considering purchasing 240's for my conversion but then remembered the 401 supports the higher rate.

[rroback]

Digital setting is really only for use when using tail specific digitals, like the 9254's. I'd go non d.s. for any other servo.

[MarkWebber]

Like Rhett said, digital's only for digital servos.

And, a faster response isn't going to be a good thing on your cyclic. All of my adjustments so far have been aimed at slowing the response of the gyros down to a managable level. Keep in mind that they will be directly aiding in cyclic input. On your tail, they don't have so much rotor disk surface to work with. Now put it on your cyclic and they'll get the heli oscillating in a big way. Like the twitch you'd get cranking your tail gain way up only the whole thing gets twitchy.

I've never used the 240's but I don't see why you couldn't. From what I've read they work well for guys that don't need remote gain. I do wonder how touchy the pot adjustments would be compared to being able to set the exact gain on a tx.

[MarkWebber]

Snuck in a flight before the storm arrives. wind 0-5mph, 20F.

I've bumped the gain from 10 to 15 and dropped the delay from 75 to 50. I'd say it's flying just about like it was with the flybar. Except for the incredible cyclic response, that is . There might be some tweaking left in the gyros, especially with a better pilot flying it. I haven't messed with the rotor phasing yet because it's difficult to tell if it's me or the phasing . I'd say it's pretty well set for now. I going to put the IR sensor on and see how it performs with stabilization. Sure could use some of that warm weather to come back. Not looking good for around here, though.

[Angelos]

Mark, you can get the phasing adjusted fairly well on the ground. The method is described in the AP-2000i user guide. Of course always check that it behaves correctly once you spool up and before you take it in the air.

4. Place any blade parallel over the tail boom and apply a large fore and
aft cyclic input while observing the blade for pitch changes. Adjust the
“Phas” menu screen until you find the number that result to no pitch
change on this blade. Keep in mind that the adjustment range is +/-90
degrees and the value you need may be negative.

-Angelos