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Old Mar 09, 2014, 12:22 AM
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Not to drag it out. Buut.

My initial reaction to the OPs post was why not. Everyone says you need lasers or barometers, which doesn't make much sense to me.

OP was talking about say flying nose first into gusty rotor winds that would bob helis up/down unpredictably.

Why couldn't a gyro with pitch accelerometer apply collective to correct instantaneous acceleration that was not commanded from the user? I realize there is further engineering than that of course, but why dismiss the concept?
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Old Mar 09, 2014, 01:07 AM
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Quote:
Originally Posted by eagle777 View Post
...
Why couldn't a gyro with pitch accelerometer apply collective to correct instantaneous acceleration that was not commanded from the user? I realize there is further engineering than that of course, but why dismiss the concept?
My gut reaction is it would work kinda like a rate mode tail gyro. It wouldn't be able to maintain a constant altitude at all. It would try to stop unwanted movement in the vertical plane, but I think the end result would be more just slowing it down?
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Old Mar 09, 2014, 01:16 AM
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Yeah, hence my 'just engineering' copout. I realize it could be in a given orientation, and you'd have to at least use trig for all 4 sensors to not make it bobble. It's probably doable with code I guess. No idea. But you do see my and OPs original question now.
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Old Mar 09, 2014, 01:43 AM
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Originally Posted by Green Darner View Post
It wouldn't be able to maintain a constant altitude at all. It would try to stop unwanted movement in the vertical plane, but I think the end result would be more just slowing it down?
If you think about it, that would be an incremental improvement in computer controlled flight. I don't know if there is something like this out there, but it isn't in the $100 or $200 range yet.
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Old Mar 09, 2014, 03:55 AM
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He was not talking about holding an absolute altitude, just lessening the spikes (see earlier posts) I assume he is flying 10-30' and doesn't want to bobble up and down. I am not sure why you all are so obtuse.
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Old Mar 09, 2014, 06:00 AM
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Cyclic gyro's alone do a fairly good job of fighting bouncing around from the wind.
I figure that if its hard enough, someone will try even when an easier known solution exists.
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Old Mar 09, 2014, 11:18 AM
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GPS doesn't give accurate altitude readings. That's what the barometer is for. The one on my Phantom is accurate to less than 2 feet. The original request can be satisfied with a decent multiwii board, which has everything but GPS for $40 - $50. All you really need is accelerometers, but since they come with the other stuff, you might as well use it.

What has been overlooked in this discussion is determining when pitch, roll, or yaw is caused by wind or is intentional. You can't determine that without some way of measuring input to those values and having some way to make decisions based on that data. None of these half-baked Ideas can do that. Naza H and APM 2.6 can do that. A multiwii board could do that with a fair amount of programming. Otherwise, you either have to activate auto-level with a switch, or turn it on all the time with very low settings. I had a rather interesting experiment with auto-level on a quad, with an MWC board. If you have a DX6i, you have to screw around with available switch setting combinations, because a DX6i has no 3 position switches and not enough two position switches for all board functions. My switch settings accidentally tied the barometer and accelerometers together, with no way to shut them off. I got the damned quad 15 feet in the air, turned on the switch and it that was it! I couldn't get it to budge until the battery ran down.

I have experimented with the MWC multiwii board on a heli and found a BeastX does a very effective job of countering wind, without needing additional help.
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Last edited by Balr14; Mar 09, 2014 at 11:55 AM.
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