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This thread is privately moderated by billpa, who may elect to delete unwanted replies.
Jan 22, 2013, 01:43 PM
Registered User
Quote:
Originally Posted by John.T
The simple explanation is that the Master Gain channel is a multiplier on the gains set in the potentiometers for each axis. When it is set to servo deflection = -100%, then that turns stabilization OFF. When you set it to +100%, then stabilization will be set to HIGH, assuming that your potentiometer gains are set to non-zeroed values. When the Master Gain channel is left disconnected, it defaults to just under what you'd get when the dial is set to 0% servo deflection (1.5ms).

I've talked with Billpa about creating a community editable document / manual for the Guardian that would compile all of the things that have been arrived at in this thread. Does anybody have any thoughts here? Many of these questions have been touched upon a long while ago, but it's easy for conclusions and advice to be lost in the discussion. A Google Doc or wiki would be an obvious idea. We want to have something that can be contributed to openly but that would be robust against vandalism. Of course, we continue to update our official manual with errors as they are reported but I'm always amazed by what the community is capable of coming up with.
Seems part of the confusion stems from using the term "multiplier". Appears it is being assumed "multiplied" always means "more" as in "multiplied" by a number >1. Multiplied is technically correct but would seem to maybe not be the best choice of wording?

Mater Gain allows you increase or decrease overall gain.

Pot settings allow you to increase or decrease gain for individual axis.

Pot settings and Master Gain work in series.

About right?

"A Google Doc or wiki would be an obvious idea" and a good idea. Would need some kind of "revision subject to approval".
Last edited by t.edwards; Jan 22, 2013 at 02:08 PM.
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Jan 22, 2013, 02:19 PM
Registered User
Galand's Avatar
After the first couple of sentences I thought that I had understood it.
Then BAM!!! "When the Master Gain channel is left disconnected, it defaults to just under what you'd get when the dial is set to 0% servo deflection (1.5ms)." Now I am lost again.

How do you get less than 0%?
Jan 22, 2013, 02:22 PM
Michael

0% means "Neutral"


I think that, by "0%" is meant the equivalent of a "neutral" servo position; i.e., the mid-point between -100 and +100, or msec range, or degrees of rotation.

Michael
Quote:
Originally Posted by Galand
After the first couple of sentences I thought that I had understood it.
Then BAM!!! "When the Master Gain channel is left disconnected, it defaults to just under what you'd get when the dial is set to 0% servo deflection (1.5ms)." Now I am lost again.

How do you get less than 0%?
Jan 22, 2013, 02:33 PM
Registered User
Prof100's Avatar
Quote:
Originally Posted by John.T
Hi All, sorry for the long silence!

To all discussing the meanings of the Master Gain vs the individual axis gains: Sorry for the confusion here and thanks for the repeated iteration on the best explanation. This can either be a confusing or a very simple topic, depending on how you approach it. The simple explanation is that the Master Gain channel is a multiplier on the gains set in the potentiometers for each axis. When it is set to servo deflection = -100%, then that turns stabilization OFF. When you set it to +100%, then stabilization will be set to HIGH, assuming that your potentiometer gains are set to non-zeroed values. When the Master Gain channel is left disconnected, it defaults to just under what you'd get when the dial is set to 0% servo deflection (1.5ms).

For those that are looking for a "calibrated" answer, I'm afraid that this is where it is honestly a little arbitrary and likely the source of the confusion. Originally, we specified that "centered" would correspond to 50% Master Gain while full deflection would yield 100% Master Gain. The channel being disconnected would equate to about 40% Master Gain, leaving stabilization on, but less likely to cause strong oscillations in the case of an accidental channel disconnect.

Upon seeing people trying to grok this nomenclature, we decided to change the language in the manual to instead make the Master Gain 100% when the slider or knob was centered, with a maximum possible Master Gain of 200%. The intention here was to help clarify that leaving this channel disconnected (giving about 80% Master Gain) would still allow for normal operation. Again, this is an arbitrary scale. I'll be the first to admit that I'm not a fan of the current nomenclature. I'm happy to help with any further questions on this and hopefully we as a group can come up with some concise language that clarifies this.

.....
Finally, some answers from a Guardian representative.

Second, your design team has created an engineering marvel.

Third, you design team is clueless about creating user friendly documentation.

Why in the world would disconnecting the MASTER GAIN provide 20% less gain? And, of course, the inverse is true. What is the rationale of doing so? The progression of setting up a Guardian most likely has a user or customer first setup the Guardian with three channels and the mode switch. Later, when a radio with a slider or proportional knob is available and enough channels are available on a receiver the MASTER GAIN would be connected. This progression takes a working setup and can quickly be a problem because invidual gains increase when Master Gain is connected. This could drive the plane into oscillation when the MASTER GAIN IS CONNECTED with the MASTER GAIN AT FULL. Your logic escapes me.
Last edited by Prof100; Jan 22, 2013 at 02:46 PM.
Jan 22, 2013, 02:36 PM
stegl

manual


A manual change would be the best for me, also. I was a little fustrated when I found out I had to use a matchbox to use a 2 servo split elevator setup when they show an auxilliary input and output which, the way I saw it, could be used as either an extra aileron servo or an extra elevator servo when in fact it looks like it is only for ailerons and should have been stated so rather than an aux in/out . The extra touch is gonna be another 65 plus bucks to make it work.
Jan 22, 2013, 02:47 PM
Registered User
Quote:
Originally Posted by Galand
How do you get less than 0%?
Negative numbers, like -100%.

What your tx is sending to Gauardian to control master gain runs from ~1.1ms, -100% (gain off) to ~1.9ms, +100% (max gain). You tx ouputs to Guardian just like it's running a servo.

If you don't have a master gain hooked up just adjust Guardians' pots.
Jan 22, 2013, 02:55 PM
2012 NZ Speedcup - 231 MPH
DownUnderPilot's Avatar
Quote:
Originally Posted by Prof100
Finally, some answers from a Guardian representative.

Second, your design team has created an engineering marvel.

Third, you design team is clueless about creating user friendly documentation.
I agree. Great product, 'A' for effort on the documentation (I didn't have to download it, and it's more than half a page), but 'C' for achievement (just look at this thread for proof!).

But what will make it better is feedback
Jan 22, 2013, 03:04 PM
Suspended Account
So the Gaurdian is working again? We now have factory support?
Jan 22, 2013, 04:10 PM
Faster is Better
OldeMan's Avatar
The dark clouds are dissipating, the sun is peeping through, and birds are chirping happily in gently swaying trees. Clarity has been achieved... and the world spins upon its axis, oblivious, sublime.
Jan 22, 2013, 04:17 PM
Registered User
Galand's Avatar
Quote:
Originally Posted by t.edwards
Negative numbers, like -100%.

What your tx is sending to Gauardian to control master gain runs from ~1.1ms, -100% (gain off) to ~1.9ms, +100% (max gain). You tx ouputs to Guardian just like it's running a servo.

If you don't have a master gain hooked up just adjust Guardians' pots.
I have three. I fly the thing all the time, set-up, pots gains, master gain etc...
Works great, I just hate poorly written documentation!
Jan 22, 2013, 04:33 PM
Registered User

An experience report


I am very impressed with my Guardian, and my second unit just arrived. Buckets of fun to come!

I wrote up a report on my experiences to date and posted it in my Club's forum.
In case anyone here is interested:

http://krcm.mywebnow.org/index.php?t...sg1705#msg1705
Jan 22, 2013, 04:59 PM
Registered User
Quote:
Originally Posted by Galand
Works great, I just hate poorly written documentation!
I agree. I think the (confusing) 0-200% description of Master Gain will haunt ET quite a while.
Master Gain is like a volume control, with off, max, and everything in between. The only value asigning numbers has is to make it easier to repeat a setting.
Jan 22, 2013, 05:54 PM
Guardian Stabilizer
Thanks for the feedback, All.

I'm going to try again on the Master Gain stuff, if you'll bear with me. I want to try and get this as clear as possible for inclusion in the manual.

The Master Gain can be treated like a master volume slider on an audio mixer board. In this example, you have three channels, one for each axis on the Guardian. Each has its own "volume" slider. Then, the Master Gain slider controls the final output volume on the entire mixer.

I can see how "multiplying" could be seen as confusing word in this context. Does "scaling" seem more intuitive?

Regarding the use of percentages, let's try different units: On a standard servo, the PWM pulse width of the signal is roughly 1.1ms for -100% deflection, 1.5ms for centered and 1.9ms for +100% deflection.

So, here is a set of ranges:
  • 1.1ms: Master Gain = 0%; Stabilization disabled
  • 1.5ms: Master Gain = 100%; recommended starting point for tuning
  • 1.9ms: Master Gain = 200%; useful for 3D maneuvers where high stabilization is needed. Strong oscillations usually happen here unless you have your individual axis gain pots turned down, are flying very slowly, have very limited control surface ranges or have a very inertial airframe.
  • Disconnected: Master Gain = 80%; Failsafe / Default; This (reduced) value was chosen to help mitigate possible spontaneous oscillations in the case of a disconnected Gain wire.

Prof100: Thanks for your feedback on the Master Gain's disconnected behavior. The intention here was to allow the Guardian to operate in as many applications as possible. Having a default Master Gain value of 80% allows for a beginning user to push their starting gains without the possibility of going wildly out of range and introducing oscillations. The expectation is that most people will fly with a Master Gain of around 100% (1.5ms), but will be able to push their performance if they want some slow speed maneuvering or similar. Getting that wire yanked at high speed and having the Guardian default to full 200% Master Gain could trigger a spontaneous and violent oscillation depending on many factors. While the Guardian detects and dampens out these oscillations, this takes a few seconds and it is still not fun to fly through that.

goldsworthy: The Guardian 2D/3D Stabilizer has always been supported by its manufacturer, Eagle Tree Systems, and even in context to this conversation about the Master Gain, it has always been "working" for its users. From what I understand, any frustration is from our documentation which I hope to remedy.

stegl: Sorry about the confusion here. This is a feature that we would love to add in future revisions of the Guardian. Stay tuned!
Jan 22, 2013, 06:27 PM
Registered User
TheBum's Avatar
Quote:
Originally Posted by John.T
  • 1.5ms: Master Gain = 100%; recommended starting point for tuning
    ...
  • Disconnected: Master Gain = 80%; Failsafe / Default; This (reduced) value was chosen to help mitigate possible spontaneous oscillations in the case of a disconnected Gain wire.
These two are telling me that, if I have the gain input permanently disconnected, I should just crank the pots all the way up from the get-go. If that's really the case, it would be nice to say something to that effect in the manual.

Oh, and "scaling" would be a good term for what Master Gain does.
Last edited by TheBum; Jan 22, 2013 at 06:36 PM.
Jan 22, 2013, 06:33 PM
Registered User
Prof100's Avatar
Quote:
Originally Posted by John.T
Thanks for the feedback, All.

I'm going to try again on the Master Gain stuff, if you'll bear with me. I want to try and get this as clear as possible for inclusion in the manual.

The Master Gain can be treated like a master volume slider on an audio mixer board. In this example, you have three channels, one for each axis on the Guardian. Each has its own "volume" slider. Then, the Master Gain slider controls the final output volume on the entire mixer.

I can see how "multiplying" could be seen as confusing word in this context. Does "scaling" seem more intuitive?

Regarding the use of percentages, let's try different units: On a standard servo, the PWM pulse width of the signal is roughly 1.1ms for -100% deflection, 1.5ms for centered and 1.9ms for +100% deflection.


So, here is a set of ranges:
  • 1.1ms: Master Gain = 0%; Stabilization disabled
  • 1.5ms: Master Gain = 100%; recommended starting point for tuning
  • 1.9ms: Master Gain = 200%; useful for 3D maneuvers where high stabilization is needed. Strong oscillations usually happen here unless you have your individual axis gain pots turned down, are flying very slowly, have very limited control surface ranges or have a very inertial airframe.
  • Disconnected: Master Gain = 80%; Failsafe / Default; This (reduced) value was chosen to help mitigate possible spontaneous oscillations in the case of a disconnected Gain wire.
Prof100: Thanks for your feedback on the Master Gain's disconnected behavior. The intention here was to allow the Guardian to operate in as many applications as possible. Having a default Master Gain value of 80% allows for a beginning user to push their starting gains without the possibility of going wildly out of range and introducing oscillations. The expectation is that most people will fly with a Master Gain of around 100% (1.5ms), but will be able to push their performance if they want some slow speed maneuvering or similar. Getting that wire yanked at high speed and having the Guardian default to full 200% Master Gain could trigger a spontaneous and violent oscillation depending on many factors. While the Guardian detects and dampens out these oscillations, this takes a few seconds and it is still not fun to fly through that.

goldsworthy: The Guardian 2D/3D Stabilizer has always been supported by its manufacturer, Eagle Tree Systems, and even in context to this conversation about the Master Gain, it has always been "working" for its users. From what I understand, any frustration is from our documentation which I hope to remedy.

stegl: Sorry about the confusion here. This is a feature that we would love to add in future revisions of the Guardian. Stay tuned!
Bold and blue needs to me inserted in v 1.8 of your manual as well as the logic behind it (your response to me). It would permit users to take the right steps as they progress from no Master Gain to using Master Gain (channel and radio permitting). Assuming 50% on Master Gain (mid point) needs to be clearly stated in your manual. I would start with full open if I consider it as a master "volume control" that only atttenuates and does not multiply or amplify the pot settings. BE CLEAR please.


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