Attention Please: DX7 Radio setup Video issue with GY401,

[Jermo]

I made a mistake in the video for the settings to control gain on the GY401 gyro in the Gyro Sens menu 0: setting. The number I gave will result in a gain setting that's too high.

To get the correct setting use the following guideline.
1% value in the DX7 = 1.5 in gain on the GY401 and GY601.

so to get 32 gain in the gyro for
Heading Hold mode:
32/1.5 = 21
50+21 = 71

Normal Mode:
32/1.5 = 21
50-21 = 29

so if to set up 32 gain for both modes the Gyro Sense settings
0:71%
1:29%

Please note these are starting settings. Regardless I apologise for getting this wrong and appreciate all the positive support I've recieved to figure this out and correct it.
Jermo

[Finless]

Jermo, I added this to the video post.

Bob

[Jermo]

ty sir. I'll try to redo that part today and upload r3 :) I'm working on the full list of The Finless Series, where do you want me to post that? It's still in work but it would give me a place to put it and edit.
Jermo

[TerryBelanger]

Moved this to the newly created 2.4 forum!!

[Jermo]

hopefully folks will actually see it here in 2.4. :dontknow
Jermo

[SC Raptorman]

If I decide to use the gear Ch for my gyro settings on the 401 will the same 1.5 % setting be the same in HH and Non HH .
I have been setting my gyro on 80 in HH ona JR radio does that mean I have to set to 53 on a DX7 to have the same settings?

[Jermo]

If I decide to use the gear Ch for my gyro settings on the 401 will the same 1.5 % setting be the same in HH and Non HH .
I have been setting my gyro on 80 in HH ona JR radio does that mean I have to set to 53 on a DX7 to have the same settings?

The answer is I believe so. We had someone run experiements with the 601 (has a display) and found that each 1% of the DX7 equals 1.5 gain for the 601 (and we assume the 401). Based on your setting of 80 on your JR that would be 80-50= 30*1.5 = 45 gain on the 401.

My question would be if you lower the setting on your JR to achieve 32 gain does your tail still hold? to get this, 32/1.5 = 21+50 = 71 for HH mode plus/minus 1 (actually equals 21.333` ). To achieve 32 gain for normal mode it's 32/1.5 = 21, 50-21 = 29 for normal flight mode.

I'd be interested in hearing how this data fits. Please indicate your rudder servo and if your tail pushrod lenght is non-standard.

Jermo

[Danal Estes]

I don't believe that's true for the 401.

On the 401, exact middle of the gain setting is zero, "above middle" is HH gain, and "below middle" is rate gain. So, for a setup like they Gyro page in JR or DX radios, where the page has values from 0 to 100, 0=max rate gain, 50= no gain, and 100=max HH gain. The formula that Jermo's given several times can map any other gain. Example: Setting of 60 = 20% because you take the 50 midpoint and subtract from 60 (60-50=10) and then double the answer because the 50 to 100 range (50 steps) has to cover 0% to 100% HH gain. You end up with 20% HH gain. Second example, a setting of 40=20% rate gain (50-40=-10, double that and your 20 steps below middle).

However... things are much simpler in the gear channel.

Since the gear channel has -100 to +100 on the endpoints, -100 endpoint=100% Rate gain, 0=No Gain, and +100 endpoint=100% HH gain. No math needed. +endpoint just "is" gain in HH, and -endpoint just "is" rate. Two examples: +60=60% HH gain. -25=25% Rate gain.

This simplicity is why I tend to believe that the gear channel is really eaisier than the Gyro page. Unless a person truly NEEDS the ability to have different gains when in different flight modes, which the gyro page makes very easy, the gear channel may actually be a better way.

At least with a 401 :)

[Jermo]

I don't believe that's true for the 401.

On the 401, exact middle of the gain setting is zero, "above middle" is HH gain, and "below middle" is rate gain. So, for a setup like they Gyro page in JR or DX radios, where the page has values from 0 to 100, 0=max rate gain, 50= no gain, and 100=max HH gain. The formula that Jermo's given several times can map any other gain. Example: Setting of 60 = 20% because you take the 50 midpoint and subtract from 60 (60-50=10) and then double the answer because the 50 to 100 range (50 steps) has to cover 0% to 100% HH gain. You end up with 20% HH gain. Second example, a setting of 40=20% rate gain (50-40=-10, double that and your 20 steps below middle).

However... things are much simpler in the gear channel.

Since the gear channel has -100 to +100 on the endpoints, -100 endpoint=100% Rate gain, 0=No Gain, and +100 endpoint=100% HH gain. No math needed. +endpoint just "is" gain in HH, and -endpoint just "is" rate. Two examples: +60=60% HH gain. -25=25% Rate gain.

This simplicity is why I tend to believe that the gear channel is really eaisier than the Gyro page. Unless a person truly NEEDS the ability to have different gains when in different flight modes, which the gyro page makes very easy, the gear channel may actually be a better way.

At least with a 401 :)

Dan, do the setup with a servo instead of the gyro, you get the expected result exactly the same..ie 50 is still center on the servo and 0/100 are the normal end points it has with the normal gear switch. Changing operation for the gear channel to be the Gyro channel behaves exactly the same way but allows you to map the operation to the TH switch (Rud D/R) OR the Flight Mode switch. What this tells me is having it straight to the gear switch OR configured for gyro is the same.

I'm not saying you're wrong, I'm saying that mapping it straight to a channel isn't any different for resolution and appears (based on my testing) that the settings should be the same. The biggest difference using the Gyro sense menu is it's scale translates -100 to +100 into 0% to 100%, at first glance this appeared to mean 1% = 2, however, on testing with another Gyro (GY601) that has a display we found the actual resolution to be approximately 1%=1.5 , Refer to the docs for the 601 and it indicates the same ranges as the 401. This leads us to the conclusion that the setup is simular enough to be considered the same.

If what you are using works then go with it.
Jermo

[kgfly]

Hmmm. I wonder if we are seeing a difference in the meaning of "100%" between radios, gyros and gyro-menu vs travel adjustment ?

Consider the following:

a) The universal servo control pulse is from 1ms to 2ms wide with 1.5ms being the centre command (0% position). Thus the full command range for a servo signal is 1ms or +/-0.5ms from the 1.5ms centre point.

b) For convenience computer radios have the concept of travel adjustment that goes beyond 100%, some go to 125% and some to 150%. How can this be if the servo range is 100% mechanical travel corresponding to a fixed command pulse range of +/-0.5ms from the centre ? The answer is that the meaning of 100% travel on each radio can be different.

From pg84 of the DX7 manual "The travel adjust range is from 0–150%.". This means they define +/-100% to mean +/-0.33ms with the extra 0.17ms providing the 50% overrange capacity.

Futaba is a bit different. From the 7c/9c manuals "Ranges from 0% (no servo movement at all) to 140%. At a 100% setting, the throw of the servo is approximately 40deg for channels 1-4 and approximately 55deg for channels 5-8."
Based on 140% corresponding to 0.5ms, their 100% must correspond to 0.36ms. However on the channel normally used for gyro control they say 100% corresponds to 55deg which means 0.46ms.

c) Now think about commanding the gyro range. We know that the gyro gain range control is split between HH and Rate around the 1.5ms midpoint. What we don't know is how Futaba define 100% gain. Is it 0.33ms offset, 0.4ms offset or 0.5ms offset ? My guess is that it is 0.46ms = 100% gain.

Now consider using simple endpoints on the JR/Spektrum gear channel. Since the logical endpoint of +/-100% is mapped to a physical endpoint of +/-0.33ms this corresponds .33/.46 = 72% with the gyro gain.

Now consider using the gyro menu. My theory is that 0 to 100% on the gyro menu corresponds to the standard -100% through +100% = 2 x 0.33 or 0.66ms range. So a 1% change in the gyro menu corresponds to 0.0066ms change in the command. If indeed the gyro defines 0.46ms as 100% then a 1% change in the gyro menu corresponds to (100* 0.0066)/0.46 = 1.44% change in gain.

Thus we can see (perhaps) how the 611 was reporting a 1.5% gain change for each 1% change in the DX7 gyro menu setting.

So if my analysis is correct (a big if!) my conclusions are:

Using a DX7 with a Futaba gyro (401 or 611):
a) Using the Gear channel endpoints is simpler to understand and gives enough operational range but due to the differences between JR/Spektrum and Futaba does not give a 1:1 mapping. Hence 100% Gear travel corresponds to 72% GY401/611 gain. Hence if you ever really wanted 100% gyro gain you would have set your endpoint to 139%.

b) Using the Gyro menu actual gyro gain is given by:

1.44 * abs(G-50) where G is the gyro menu value (0 to 100).

eg G = 30, Rate gain = 1.44 * 20 = 29%
eg G = 75, HH gain = 1.44 * 25 = 36%

---------------------------
Of course this is all speculation that would be easily cleared up with access to the equipment and an oscilloscope but I don't have either.

[Jermo]

:noteworthy

Simple experiments so far show servo travel is 100% the same using the simple gear switch vs using the gyro menu. other than that ty for the numbers/data. Nicely presented.
Jermo

[kgfly]

Jermo,

If you are saying +100% travel on simple Gear channel setup gives the same servo deflection as 100% in the Gyro gain menu (and -100% travel the same as 0% in the gain menu) then that makes sense and agrees with my theory. I presume if you set the Gear endpoint to %150 you see more mechanical travel than with the gyro gain at 100%, is that right ?

[Jermo]

Jermo,

If you are saying +100% travel on simple Gear channel setup gives the same servo deflection as 100% in the Gyro gain menu (and -100% travel the same as 0% in the gain menu) then that makes sense and agrees with my theory. I presume if you set the Gear endpoint to %150 you see more mechanical travel than with the gyro gain at 100%, is that right ?

I didn't mess with end point travels at all. The only thing that still doesn't make sense is the 1% travel being equal to 1.5% gain instead of it being 1:2 as expected.
Jermo

[DavidH]

It is the same on a few radios when using the GY gyros.

0-50 is Normal or AVCS and then 50-100 is the opposite of 0-50.

100% ATV would be 100% gain in either AVCS or Normal
0% would be 100% gain in the opposite mode from the 100% mode.

And 1% ATV would equal 2% gain change.

For example 90% ATV would be 80% gain in one mode or the other
And 10 % ATV would be 80% in the opposite mode.
At least that has been my experience over the years when using the GY with some radios.

David

[Finless]

b) Using the Gyro menu actual gyro gain is given by:

1.44 * abs(G-50) where G is the gyro menu value (0 to 100).

eg G = 30, Rate gain = 1.44 * 20 = 29%
eg G = 75, HH gain = 1.44 * 25 = 36%


KGfly.... this is right on man... Our tests (as you saw int he other post) showed this was the case with a 601 gyro display. But there was some varience to the 1.5 I came up with which as you say is probably closer to 1.44 per your calculations!

Awesome job!

BTW it appears the 9303 is exactly the same using the gyro menu as I played with that on axxis's heli yesterday and got the same results.

Bob

Bob

[500Driver]

So if a new guy using a S9650/401 is getting a tail wag at 'X%' and bumps it down 1% resulting in a loose...even slow left yaw...what would the guru's of the gyro suggest? :)

Could this be a mechanical set-up issue at this point?

Thanks all for your continued support and help,
- Don

[Jermo]

500Driver it depends if the "wag" is a hunt or the tail coming loose, remember we have a few more adjustments available...namely the Gyro gain ON the gyro and delay. For a digital servo we want delay to zero. (note: I'm just parroting what I've learned and how mine works. If Bob or one of the more experienced guys disagree's with me definately go with thier advice.)

Jermo

[kgfly]

Jermo

The only thing that still doesn't make sense is the 1% travel being equal to 1.5% gain instead of it being 1:2 as expected.
I think you need to reread my analysis. The 1:1.5 you saw is most probably due to the different definitions of "100%" between JR/Spektrum and Futaba. The Spektrum defines the 100% command position as 0.33ms offset whereas on the gyro gain channel Futaba define it as 0.46ms. Hence giving 0.46/0.33 = 1.4.

David

I agree with the simple mapping you describe but I am guessing that, depending upon the radio being used, 100% ATV does not actually correspond to 100% gyro gain. However since you never really want 100% gain that doesn't matter. Most people report operating HH around the 25% to %40 range. On a JR/Spektrum I believe this is actually 18% - 29% gain for a Futaba gyro. Since it is a matter of adjusting to get the right flight performance, the absolute numbers don't really matter so long as there is enough adjustment range which clearly there is. If your experience with 601 gyros (which report the gain command they are sensing) is that the reported gain matches the ATV setting on a JR radio then I guess that invalidates my theory on that radio model which would be interesting to know.

[Danal Estes]

Agree that for various travel/endpoint/pulsewidth reasons, 1 point on radio could end up being 1.x on gyro.

Cannot agree that, on a DX7 (which is the radio with which this thread started) the Gyro page 0 to 100 range sets up exactly the same as Gear channel's -100 to +100 range. Gyro page has only 100 steps... gear endpoints have 200 (ok 201 if you count the zero in the middle). Cannot be the "same".

Also, I do not beleive that a 401 and 601 map gain exactly the same way. I will restrict my comments to a 401.

Pictures are much easier than words. On the DX7 Gyro Page, a GY401 will see:

0 10 20 30 40 50 60 70 80 90 100 Radio
100 80 60 40 20 0 20 40 60 80 100 Gyro
|--------Rate--------|---------HH---------| Gyro


Or very close, as 100 on radio may not perfectly match to 100 on Gyro for pulse width reasons as shown by Kgfly, but let's ignore that for now...

And on the DX7 gear page:


-100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 Radio
100 90 80 70 60 50 40 30 20 10 0 10 20 30 40 50 60 70 80 90 100 Gyro
|------------------Rate------------------|-------------------HH------------------| Gyro


Again, "very close"... same reason...


I find the Gear mapping shown above to be MUCH easier to grasp in my head without the diagrams... so if you need flight mode switching, by all means use the gyro page. If not, gear endpoints certainly seems easier to understand: Negative numbers are rate mode gain, positive are HH gain.

[STAN-LEE]

IT'S EARLY AND I NEED TO KNOW IF THE STATS. IN FINLESS T-REX VIDEO ARE THE CORRECT ONES TO FOLLOW? I SET UP JUST LIKE HE DESCRIBED IN DX7 SET UP WITH MY 401 I FOLLOWED EVERYTHING HE SUGGESTED TO DO :arggg: I'M JUST WAITING FOR DEFECTIVE PARTS TO BE REPLACED. I HAVENT DONE ANYTHING WITH HELI YET EXCEPT BUILD BEFORE I FLY I'M SEAKING A INSTRUCTOR TO HELP.THANK YOU T-REX 600 CF

[Jermo]

Stan,
Buddy, find the caps lock key and turn it off. Typing in all capital letters is considered yelling. IF you download Finless GY401 video and my DX7 video you are all set. Use the numbers I show in the DX7 setup video. Those are starting points. Make sure you have version 3 of the video. If you have any problems please feel free to post in the newbie forum or the T-Rex section for the 600.

To my knowledge the gain for the DX7 and the T-Rex 600 is higher than for the T-Rex 450. There are several posts in the T-Rex 600 section discussing the GY401 on the 600.

[STAN-LEE]

thank-you stan

[wgregww]

Stan,
Buddy, find the caps lock key and turn it off. Typing in all capital letters is considered yelling. IF you download Finless GY401 video and my DX7 video you are all set. Use the numbers I show in the DX7 setup video. Those are starting points. Make sure you have version 3 of the video. If you have any problems please feel free to post in the newbie forum or the T-Rex section for the 600.

To my knowledge the gain for the DX7 and the T-Rex 600 is higher than for the T-Rex 450. There are several posts in the T-Rex 600 section discussing the GY401 on the 600.

Jermo, can you please tell me were this video of yours is at on the DX7? I looked under the 2.4Gz shouldn't it be at the top?

[kgfly]

Greg,

You will find it linked off the Finless Tech Room page: http://www.helifreak.com/viewforum.php?f=95
http://www.helifreak.com/viewtopic.php?t=30926

[Timberwolf]

Hey Folks,
I'm just finishing my V2 and to the point of setting the 401. I truly am thankful for the effort's of the finless series and jermo's DX7 vid. as well as hrs of reading other posts on this site, they have been very helpful.
Am I to still understand after all this tech talk that a good starting point under Gyro Sensing Menu on DX7 for gain is STILL 72% on both settings (blinking 0 and 1) with F Mode all set for 0 which would be HH as I understand in the gyro portion of jermo's vid? With my 401 I have moved the DS switch from off to on for my 9650 and found I did have to switch the REV for proper dir. I have the 6000 rx currently installed. Under INPUT SELECT, GEAR/GYRO is set.
Now my problem, I watch the fin's video for checking and reversing of the gain channel in the radio, and mentions switching CH 5 or GEAR if Gyro is blinking. to aquire HH mode when initializing gyro on startup. Mine started up in HH mode with solid light, for all F Mode switch positions whether I reversed Ch 5 or not, or flipping the gear switch on the radio, so I can't tell if i'm reversed or not. I wanted to TRY to replicate a blinking start up mode as per vid. and then reversing back. I could not replicate unless I brought the RATE down below 50 % in GYRO SENSING menu. But figured that was not right... so back to 72% on the settings but cannot get the gyro to switch OFF to set Limits with FMode switch to normal as per video.. Am I to understand that you need to be able to switch the gyro "off" 1st to set the Gyro limits via radio flight mode switch in Normal mode and then adjust Gain limiter on gyro? This is not working, the light will not go off.
Nothing seems any different if I flip the Gear switch on the DX either...I'm also not sure when and if the gear switch is used or what that would be for, could one elaborate on this a bit...
Also when all is powered up, (motor unplugged) and with HH mode when I power up as per LED..... I move the Collective stick around and Gyro light is flashing randomly all the time, is this normal as if jumping in and out of HH mode????
Any thoughts would be appreciated........

It's all about attitude, airspeed, and angle of attack!!!

Thanx!

TRex 450 SE NV2, DX7, AR6000, GY401 :bomb: