Espritmodel.com Telemetry Radio
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Old Aug 04, 2012, 08:00 AM
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Time to beat a dead horse


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I believe the above weould work fine with a new unflown / untrimme3d new model if when you do the Reset Level Trim you in fact have the model at exactly the same level as it was in the first attempt.
That sounds correct. I agree.

Quote:
My thinking and past experience based on my somewhat limited retriming experience with Guardian is that if the aircraft was flown and trimed prior to installing Guardian and initial Set Level was close enough that in 2D the aircraft did not do anything of a violent nature when enabled but likely aircraft pitched up or down slightly then merely trimming in flight with the Transmitter trims and doing a Reset Trims only after landing resulted in a properly trimed Guardian.

http://www.rcgroups.com/forums/showp...&postcount=855
I'm still not in agreement here and here's why and how I understood it:

If you add/subtract the Trims in the Tx while the Stabilization is in 2D, then it may look like it is level but it will only be true while you haven't done the Reset Trims Only procedure. Also, it may make the 3D to behave unpredictably because now, to the Guardian, it will look like the stick in not in the center. And, it will also disturb the level flight attitude when stabilization is OFF. Remember, the Trim is stored in the Tx not the Guardian.

Then, when you land and do Reset Trims Only, what it does is telling Guardian that this is the new neutral/center stick position but not the new 2D Level Flight position. So, now your 2D and 3D will work normal again but your Level FLight in 2D has not changed. On the other hand, your Level Flight with Stabilization OFF is already offset because the Trim value is still in the Tx.

The Level Flight position (again to my understanding and based on little experience with another brand) is dictated by the values obtained from the Accelerometers, not from the Tx signals. So, the Tx Trim will not affect it. The only time the Accelerometer value are changed is by physically positioning the model with the Guardian in it.

If there is a way to alter these stored values in the Guardian thru some signals from the Tx then that maybe another way to resetting the level flight without going thru all the bench work, but I don't think it is available right now.

Well, I hope @billpa or @John T can comment and I welcome any correction to my statements above.

Thanks,
Rico.

Edit: Sorry. I missed the link in Charles's original post which I quoted... I just put it in now. Which, BTW, I agree with the content in that link.
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Old Aug 04, 2012, 08:08 AM
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I retitled a prior post since I was in a bit of a hurry to get on the road for a little r&r in Northern Michigan.

The title should have been "DIY Current Meter and info on Digital Servos". Here is the post with links just in case you missed it, http://www.rcgroups.com/forums/showp...postcount=1264

The current meter looks easy to bui ld, and so I definitely will add it to my build projects. Such a tool should at least provide a much closer approximation to the question of whether your system is pulling to much amps.
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Old Aug 04, 2012, 08:21 AM
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Haralson County GA. USA
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Rico you failed to copy the link I included at the bottom of my post . I shall not debate the effects that triming in flight has on the Guardian in 2D or 3D if done with Trans. while in 2D mode. As I have posted I do not believe in using Trans. trims for trim except during flight for the sole purpose of determing where the surfaces need to be mechanicaly adjusted to on the ground.
After in air trimming I land note position of a control surface,set that channnel trim back to zero and adjust the linkage to place surface back to where is was prior to setting Trans. trim back to zero.

I have been know to fly multi aircraft with a single Trans. when in fact the trans. had no model memories , no D/R, no expo.no sub trims and not even any servo reversing.


For those who want the ability to check and see for sur if their power source for their receiver,servos and Guardian 2D / 3S is up to the task or not I knopw of no better device. I own and use one with all new setups and I know several who have used them and have credited this device with saving one or more of their models. Great news also as the price is now close to 1/2 of what myself and others paid for them in the past. I guess due to the fact that some receivers have this function on board now the price is being driven down.

http://www.xtremepowersystems.net/pr...=XPS-TT&cat=10


Charles
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Old Aug 04, 2012, 10:56 AM
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Servo Current Draw with stabilizers

I knew that stabilizers make the servo's draw more currrent but I did not realize it could be so bad.
This from the site:
http://www.societyofrobots.com/actuators_dcmotors.shtml

"Power Spikes
There is a special case for DC motors that change directions. To reverse the direction of the motor, you must also reverse the voltage. However the motor has a built up inductance and momentum which resists this voltage change. So for the short period of time it takes for the motor to reverse direction, there is a large power spike. The voltage will spike double the operating voltage. The current will go to around stall current."

I guess that this is what happens when the stabilizers continuously and rapidly make the servos change direction around the neutral, which is how they operate.
If you installed four of the popular HXT900 that would draw 4x700mA or more than 2.5A.
That's more than most linear ESC BECs can deliver on 3S thus possibly making the Rx brown-out.
I lost the source for the attached chart, sorry.
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Old Aug 04, 2012, 11:06 AM
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Originally Posted by jedorme View Post
I just test flew my PZ T-28 with my Guardian for the first time after everything checked out fine on the ground. Took off with 3 position mode switch in off & at about 2 mistakes high I switched on 2D; immediately I got very erratic behavior instead of stabilization; so I switched off & recovered level flight; then thinking because I reversed the Mode switch channel to put 2D on top, I switched to 3D & the A/C snapped into a spin! By the time I got the stab unit off, pulled the power & began recovering I was on the ground off the end of my grass runway in some heavy cut hay, resulting in some repairable damage to the nose area. But it was such a shock after everything I've read on this site & after everything seeming to be working as required in both modes while ground checking it - all servos & control surfaces moving right direction & only moderately. I have the pot gains at 50% with the master gain wire unplugged, so 40% default times my 50% set should be about 20% actual gain which seemed right for this A/C.

Is it possible that when switching between off to 2D to off to 3D to off that I may have inadvertently caused the unit to reset level flight & trim again over what I set on the ground? Also do you need to reset level flight & trim before each flight? I read the manual that this wasn't necessary, but I did this setting the day before I actually flew it. Anyway, most distressing & confusing as to what to do now. My confidence in the unit is not nearly as great as before, at least until I can figure out what went wrong. Needless to say the other fellows I was flying with weren't very impressed either.

Jed
I would guess you had a gain/response reversed. Been there done that.
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Old Aug 04, 2012, 11:32 AM
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Haralson County GA. USA
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OT

Deadstick nice to see another SS as an avitar.

I am the proud owner of three Ace microPro 8000s but only one is a SS which I purchased new when they were first released.

Charles
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Old Aug 04, 2012, 11:34 AM
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jedorme,
is your t-28 constructed of some type of foam? are you still mounting the stab unit with velcro? velcro, especially cheaper hook and loop fasteners can allow minute movement to motion sensitive electronics. i've yet to see a gyro (haven't seen them all) come with velcro mounting. most all seem to have double sided tape or a gel pack and if your plane is made of foam the
vibrations from the motor, turbulence etc... are amplified more than on a balsa plane. you would think foam would dampen these vibrations...
mems gyros are supposedly less affected by vibrations, temp. changes etc... but not totally the last assan mems gyros i bought came with solid metal plates to mount the double sided tape to, which you mount the gyro to. i personally use lite ply epoxied to my planes then clean with alcohol and
then apply 2 layers of 3m #4011 gray urethane exterior double sided tape and affix the gyro to that. no glue or anything else needed and it won't come loose even when hitting a non movable object at near full speed.
fwiw - this great wealth of gyro knowledge that i have imparted here i owe to melnic and his "using gyros on an airplane" thread.
it sounds like you bought a cc 10 amp ubec from jeff. in case you didn't know the cc10 amp ubec is actually a 7 amp continuous, 10 amp peak ubec. imo, the best bang weight and amp wise for your particular currency.

michael clyde
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Old Aug 04, 2012, 11:57 AM
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galand,
the "max current (ma)" line on your chart is the max current it will pull under normal operating conditions not what current it will pull under "stalled" conditions, right? i was thinking those tower pro 9g's were over and amp when run hard aground. i know they are some current pigs.
nice link on dc motors, although i do not condone (nor have i ever) the crushing of kittens, at least not in public.

michael clyde
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Old Aug 04, 2012, 12:18 PM
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Originally Posted by mchldpy View Post
galand,
the "max current (ma)" line on your chart is the max current it will pull under normal operating conditions not what current it will pull under "stalled" conditions, right? i was thinking those tower pro 9g's were over and amp when run hard aground. i know they are some current pigs.
nice link on dc motors, although i do not condone (nor have i ever) the crushing of kittens, at least not in public.

michael clyde
I think you are right. From the other chart it looks like 750mA is the peak draw for HXT900.
What I think is remarkable in this chart is the difference in draw between a short and a long pulse.
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Old Aug 04, 2012, 12:30 PM
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yeah, i think that's due to analog servos not developing full torque until they have been moving. (ramping up) short pulse = motor not on long enough to draw much current. long pulse = motor on long enough to actually start sucking some amps. digitals probably don't read like that since they supposedly hit full torque (sucking amps) @ 1* off center, basically as soon as they start moving.
of course i could be wrong and have it all confused with something else.
after all, i am from texas

michael clyde
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Old Aug 04, 2012, 01:12 PM
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Quote:
Originally Posted by everydayflyer View Post
OT

Deadstick nice to see another SS as an avitar.

I am the proud owner of three Ace microPro 8000s but only one is a SS which I purchased new when they were first released.

Charles
Charles, that is a microstar 2000 I put together. Absolutely amazing radio. Put together from parts gathered all over the internet. The stick is a hand made unit from Andy Horka (jazzboy here), and to me, makes the radio irreplaceable.
I assume you are on the user group for it? The encoder design is a work of art also. I hacked a Spektrum RF deck and use a antenna from XPS. Bought the case for $10 from a member.

Between not getting enough time, and just plain issues, learning 3D flight has been tough. I am further hampered by no one else that I know is flying SS that is a decent 3D pilot. I hope to use the Guardian as a training aid in this regard, slowly lowering the gain (via the handy slider on the side of the transmitter) until I don't need it anymore. (see, I bet they thought it was thread drift here, but no, I saved it!)
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Old Aug 04, 2012, 01:55 PM
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i've been trying to follow and keep up with this achieving level flight and resetting trims and turning off the guardian in flight and using tx trims and then land and ...
i think some people think when you "turn off" the guardian in flight, not 2d or 3d but the off position on your 3 way switch, that you are actually turning off the guardian. it's not off by any means. i'm ASS-U-ME-ing it works just like any other gyro with a gain wire where on a spare channel with a vr knob you can go from +100 rate mode to zero to +100 in hh mode. zero being off. zero is not actually off. the unit has just lowered it's overall gain down low enough that it will not affect flight. if it was truly off, when you turned it back on it would go through it's initialization process of finding center of the servos, level attitude etc.... you can't do that while flying, even in a perfect world. the guardian manual says (i'm paraphrasing here) when the guardian is off it allows all tx inputs to pass through...", the guardian is not off. it's just turned down so low that it's not going to affect flight. the manual is partly to blame for this mis-interpretation of "off" or "disabled". i'm also ASS-U-ME-ing that memory of level flight and trims is kept in eeprom or whatever the type of memory is that doesn't need power to retain what's been put in it.
BUT, i could have my head stuck up my duckplucker and be wrong about everything.

michael clyde
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Old Aug 04, 2012, 03:02 PM
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Quote:
Originally Posted by mchldpy View Post
i've been trying to follow and keep up with this achieving level flight and resetting trims and turning off the guardian in flight and using tx trims and then land and ...
i think some people think when you "turn off" the guardian in flight, not 2d or 3d but the off position on your 3 way switch, that you are actually turning off the guardian. it's not off by any means. i'm ASS-U-ME-ing it works just like any other gyro with a gain wire where on a spare channel with a vr knob you can go from +100 rate mode to zero to +100 in hh mode. zero being off. zero is not actually off. the unit has just lowered it's overall gain down low enough that it will not affect flight. if it was truly off, when you turned it back on it would go through it's initialization process of finding center of the servos, level attitude etc.... you can't do that while flying, even in a perfect world. the guardian manual says (i'm paraphrasing here) when the guardian is off it allows all tx inputs to pass through...", the guardian is not off. it's just turned down so low that it's not going to affect flight. the manual is partly to blame for this mis-interpretation of "off" or "disabled". i'm also ASS-U-ME-ing that memory of level flight and trims is kept in eeprom or whatever the type of memory is that doesn't need power to retain what's been put in it.
BUT, i could have my head stuck up my duckplucker and be wrong about everything.

michael clyde
Well, for one thing, the Guardian unit itself has to be powered ON at all times while in flight because that is where the servos are connected. Also, it has to be ON and awake all the time, otherwise, how would it know when you move the Mode Switch in the Tx from one mode to the other.

Personally, I always understood that when the manual refers to Stabilization OFF it means just that... Stabilization is OFF... meaning the stabilization algorithm or logic (or watever it is that pertains to stablilization) is not being applied but the unit is ON and awake... I've always interpreted it that way and always assumed that everyone else understood and interpreted the same.

But good point in pointing that out... maybe some (although I doubt if there are many) may have been thinking that the unit is OFF when the manual refers to Stabilization is OFF, which is not really the correct interpretation.

Thanks,
Rico.
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Old Aug 04, 2012, 04:35 PM
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Off is easier to say than gains turned down to zero.
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Old Aug 04, 2012, 04:44 PM
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you are correct rico,
i just read the manual again and it's referred to as "stabilization off or disabled" nowhere do they refer to it as guardian off. so maybe i'm the only one who thought that "someone" might think they meant the whole thing was off. i still don't think it's off or disabled, just the overall gain is so low it's output won't affect flight or else how could they turn it back on without it needing to go through the initialization process, although the internal config file it writes to may be in depth enough to tell itself what it needs to know without initializing.
the one thing i'm absolutely certain about is that i'm absolutely certain i'm not real sure about much.
i'm going to go and try real hard to pull my head out just a little.

michael clyde
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