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HomeAircraftHelicopterHelicopter Main Discussion › Gpro VS Vbar
10-24-2014 02:04 PM  3 years agoPost 101
HeliNutAndy

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worcester, MA USA

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Is the Gpro vibration resistant or does it have any issues on a gasser or nitro model? I was wondering if anyone had any good or bad experiences? I have a gas project I'm working on and haven't decided on a FBL controller as of yet. I really like Aligns software interface for the Gpro. I've only used it in test mode but it is pretty slick.

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11-18-2014 01:10 PM  3 years agoPost 102
MrMaster

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Africa

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Well as far as I know its perfect

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11-19-2014 01:52 AM  3 years agoPost 103
EEngineer

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TX

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I'm talking about reaction time between moving your hand and you eyes noticing it moving! Pretty instantaneous!
Not really....

The eye/brain interface has a "frame rate" of about 10 to 13 per second....Couple that with the time it takes to react to an "image" change....far from instantaneous.

This visual delay is how TV signals are manipulated to suit our vision.

FWIW

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11-19-2014 01:56 AM  3 years agoPost 104
EEngineer

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TX

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I always liked a little tail wag!
Heel spot.....

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11-19-2014 07:34 AM  3 years agoPost 105
Richardmid1

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Leeds, England

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This visual delay is how TV signals are manipulated to suit our vision.
Your misunderstanding this, that is a visual change from an outside source that we have no control of or can preempt.

You see your own hand move instantaneously because your brain has already told it to move.

I'm not too good at explaining things but is that clearer?

60% of the time, it works every time!

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11-19-2014 08:16 AM  3 years agoPost 106
EEngineer

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TX

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Not really...and you're incorrect...

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11-19-2014 10:51 AM  3 years agoPost 107
Retired2011

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Lee's Summit, MO

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The eye/brain interface has a "frame rate" of about 10 to 13 per second....Couple that with the time it takes to react to an "image" change....far from instantaneous.
That's what I'm saying...
in that amount of time the Vbar has made more calculations than it takes to do Chinese arithmetic.
There is no way you can out maneuver it.

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11-19-2014 11:58 AM  3 years agoPost 108
Richardmid1

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Leeds, England

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There is still confusion as to what im saying!

You guys are thinking in terms of the helicopter reacting to wind gusts etc., im talking about it reacting to your own input where if it were connected to strings for instance it would move instantaniously to your inputs, but it doesn't, it's that delay im talking about and it can be felt, it just can, fact!

60% of the time, it works every time!

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11-19-2014 12:08 PM  3 years agoPost 109
Climax

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West London, United Kingdom

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Most flybarless system aren't just simple PID loops regardless of what people say or claim! (if they were they wouldn't work very well...)

They have to cope with extreme levels of vibration (mainly from the main rotor, especially acute on the aileron as its axis has less inertia) and also relatively long delays between control input from the servos to actual response from the rotor (10s of milli seconds, which is also head speed dependent - this is a long time in the context of real time control!!)

To overcome the delay most controllers will implement a "model" of the helicopter's response, this is then delayed appropriately and compared with what the gyro are actually sensing in order to figure out if the corrections made by the loop are appropriate.

In the absence of external perturbations the delayed "model prediction" should match what the gyros actually report. Any differences are due to wind etc. and can thus be determined and corrected by the loop on the next iteration.

For this to work the internal "model" of the helicopter needs to be reasonably good. This is also often where some of the flybarless simulation is implemented.

So in this sense the controller knows what the helicopter should do (i.e. is about to do) and then waits to see if it happens, if not tries to fix it...

You can't get away from the delays, you have to work with them!!

Designing good flybarless controllers is hard, very hard!! (I know 'cos I've been through the pain barrier - details in my gallery...)

Don't know if this helps?

Electronics, Physics, Helicopters, Fixing Things...

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11-20-2014 02:16 AM  3 years agoPost 110
BobOD

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New York- USA

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The eye/brain interface has a "frame rate" of about 10 to 13 per second
Consider this. The overall delay is the sum of all. So, just picking #'s, if rate of perception is 100ms and the controller adds 20ms to that, there's a 20% difference in what the brain expected and what it saw. 20% is quite noticeable.

Further, above a certain frame rate, human perception will not notice it. That is, it can comfortably adapt. However, the brain will be able to notice much smaller differentials. For example, to fly one heli and then another. Much like the (attached by a string) analogy Richard mentions. It's hard to say, yes...I'm seeing a delay, but you can tell there is something different.

Then there is variability on the fly. Human perception can detect this to even smaller time scales. For example, when the delay increases for a moment when the FBL controller is doing more "thinking" in certain situations than others. Some are more quircky than others in this regard.

And, of course this depends on experience.
Here's a simple example of that. Most anyone can tell the difference, at a glance, between 3 marbles and 2. But not 100 and 99. But, with enough practice, you could.

Team POP Secret

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11-20-2014 02:23 AM  3 years agoPost 111
EEngineer

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TX

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Consider this. The overall delay is the sum of all. So, just picking #'s, if rate of perception is 100ms and the controller adds 20ms to that, there's a 20% difference in what the brain expected and what it saw. 20% is quite noticeable.
That's what I meant....

The other analogy is incorrect....for you brain to tell your fingers how to move, it must first sense where to move them.

It was stated that this was instantaneous....and it's not.

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11-20-2014 02:41 AM  3 years agoPost 112
BobOD

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New York- USA

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Indeed...but I believe he said "pretty instantaneous".

Team POP Secret

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11-20-2014 04:50 AM  3 years agoPost 113
EEngineer

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TX

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I believe he said "pretty instantaneous
Your thinking reaction time as in reaction to say a goalie during a penalty. I'm talking about reaction time between moving your hand and you eyes noticing it moving! Pretty instantaneous!
You're exactly correct, Bob....

As I understood the analogy explanation, I thought the lagtimes were not properly considered.

See the helis orientation...and then react....equally "visual/mental processing lag time".

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11-20-2014 04:53 AM  3 years agoPost 114
EEngineer

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TX

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BTW, with the "goalie" analogy...

In the penalty kick phase, a goalie is intentionally "faked" out by the body language of the striker.

A heli doesn't "fake you out"....it's on your team....

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11-20-2014 07:53 AM  3 years agoPost 115
Richardmid1

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Leeds, England

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The other analogy is incorrect....for you brain to tell your fingers how to move, it must first sense where to move them.
The brain already knows where to move them, you know what your next movement is going to be during tick rocks etc.

60% of the time, it works every time!

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11-20-2014 08:23 AM  3 years agoPost 116
EEngineer

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TX

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With all due respect, your analogy is incorrect...

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11-20-2014 09:05 AM  3 years agoPost 117
Climax

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West London, United Kingdom

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The brain is most definitely predictive with respect to co-ordination! Some of its predictive abilities are hardwired other are learnt.

It is also very good at knowing the position of things like hands, fingers, legs, feet etc. This position knowledge isn't perfect as with all systems is subject to noise.

The combination of the above two capabilities allows us to do things like reach out of view to pick something up, decide weather or not we're going to get hit by a car when crossing the road, catch a ball, etc.

So surely this mechanism is going to massively help us when doing something like a TicToc, that is once you've learnt how to do it! It becomes a complex reflex involving vision, muscle memory, spatial positioning and prediction...

In very general terms control systems use prediction when dealing/coping with delays, however small, if they are significant with respect to desired response time.

Electronics, Physics, Helicopters, Fixing Things...

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11-20-2014 09:10 AM  3 years agoPost 118
EEngineer

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TX

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Sounds like some heavy mamba jamba....

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11-20-2014 09:26 AM  3 years agoPost 119
Climax

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West London, United Kingdom

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mamba jamba
Never heard that term before! But them I'm a Brit...

Electronics, Physics, Helicopters, Fixing Things...

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11-20-2014 10:15 AM  3 years agoPost 120
Richardmid1

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Leeds, England

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I understood and he is correct.

In a car with electronic fuel injection when you step on the throttle you know how far and fast you have pressed that peddle, so there is virtually no lag there. Yet the response from the car is not in time with your foot movement, there is a slight lag, of course this lag differs from car to car make as it does with fbl controllers! Whereas if the car is old and has a mechanical carb there is a direct link between foot movement and carb opening so that is alot more instantaneous!

60% of the time, it works every time!

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