Control gyro gain with throttle trim

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willhac
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Control gyro gain with throttle trim

Post by willhac » Wed Mar 25, 2015 5:32 pm

The new manual gave me the idea of controlling gyro gain with throttle trim on helicopters and I find it wery usefull for adjusting gain during flight.
Throttle trim is set to off in mixers, as a source of GVAR1, and GVAR1 as a source of CH6, gyro gain for me. It work very well.
But I have to set the trim inc. to "exfine" (steps of 1) for the gyro, and I'd like to keep it set to "medium" (steps of 4) for real trimming of elevator and ailerons.
My question is : is there another way with mixes and logical switches to use these throttle trim buttons (to act as push buttons ?) to increment/decrement a GVAR or a value in a mix ?
Last edited by willhac on Wed Mar 25, 2015 6:31 pm, edited 1 time in total.

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jhsa
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Re: Control gyro gain with throttle trim

Post by jhsa » Wed Mar 25, 2015 5:50 pm

Interesting idea I would say ;)
I didn't test this, but are you sure that the trim increments setting affect it when used as source to a GVAR?
If they do maybe it would be better if they didn't?

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willhac
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Re: Control gyro gain with throttle trim

Post by willhac » Wed Mar 25, 2015 6:14 pm

Yes I confirm they affect in r815 & latest r817_test.
I agree with you, perhaps it would be better if the trim inc. settings were inhibited in that case ?
Last edited by willhac on Wed Mar 25, 2015 6:30 pm, edited 1 time in total.

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jhsa
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Re: Control gyro gain with throttle trim

Post by jhsa » Wed Mar 25, 2015 6:23 pm

Let's see what Mike says about it..
We now have GVAR adjusters if we need increments other than 1. Still not available for the 9x I believe?? At least not in the same way as in ersky9x..

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MikeB
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Re: Control gyro gain with throttle trim

Post by MikeB » Wed Mar 25, 2015 7:35 pm

Interesting "feature". It happens due to the way the gvars are implemented, they just pick up the current (flight mode specific) trim value. I must admit to always using exFine for my trims.

This might take some thought to come up with a good solution.

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jhsa
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Re: Control gyro gain with throttle trim

Post by jhsa » Wed Mar 25, 2015 7:52 pm

I normally use "Fine" for the trims..

Crazy Idea, I mean really crazy ;) What about treat The 2 trim switches (ex: Up trim, down trim) separately as 2 different switches? They could be used as 2 different momentary switches. It would have to be a very special feature I guess.. Maybe even only the trim assigned to a throttle input?? Maybe too confusing?

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willhac
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Re: Control gyro gain with throttle trim

Post by willhac » Wed Mar 25, 2015 8:13 pm

Confusing but convenient !
Or perhaps the new switches/buttons (PB1/PB2) Mike is working on will be more adapted for doing this ?

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Re: Control gyro gain with throttle trim

Post by jhsa » Wed Mar 25, 2015 8:22 pm

yeah, I'm planning to install 2 push buttons on the back of the tx that I can easily access without letting go of the controls..
If I would design a completely new radio for thumb flyers that's where I would probably put the trims :D

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Re: Control gyro gain with throttle trim

Post by bob195558 » Wed Mar 25, 2015 8:29 pm

I have a FrSky Smart Port GPS Sensor and if this GPS could do this, I am interested in this too.

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MikeB
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Re: Control gyro gain with throttle trim

Post by MikeB » Wed Mar 25, 2015 11:59 pm

It seems this may be tied in with adjusting a GVAR in general. If a trim switch could be made available as an increment/decrement input to a GVAR, I think this would provide a good solution for this problem.

It won't be something I can put in quickly though, it will need more thought as to how best to implement it.

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Re: Control gyro gain with throttle trim

Post by MikeB » Thu Mar 26, 2015 12:11 am

I've just checked the code. There is a bit of a fiddle you can do that might help. If you turn "Throttle Trim" on, then the trim step size for the throttle channel is forced to "fine" (step size of 2).

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willhac
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Re: Control gyro gain with throttle trim

Post by willhac » Thu Mar 26, 2015 8:23 am

Thanks for the info, "fine" may be enough for adjusting gyro gain, I'll try it.

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Re: Control gyro gain with throttle trim

Post by MikeB » Thu Mar 26, 2015 9:28 am

Also, do you need the full 'throw' on the gain channel? If you use, say, 50% of GV1 as the source, does this give enough adjustment? You could also use an offset in the mix to move this amount of adjustment to where it is needed.

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willhac
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Re: Control gyro gain with throttle trim

Post by willhac » Thu Mar 26, 2015 10:40 am

Yes it should do the trick : tail lock gains are between 0 and +50 on the gyros I have, so no need for an offset.
I'll try all that this evening !

Will

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MikeB
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Re: Control gyro gain with throttle trim

Post by MikeB » Thu Mar 26, 2015 10:50 am

If you only need 0 to +50, then this is only 25% of -100 to +100. You could therefore use:
+25% GV1 Offset 25%.
The channel output will then go from 0 to +50%.

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willhac
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Re: Control gyro gain with throttle trim

Post by willhac » Thu Mar 26, 2015 11:40 am

To resume, if I understand well, if I use :
+50% GV1 Offset 50%
...the channel output will go from 0 to +100%, and with "Throttle Trim" on, I will have a step size of 1 ?

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MikeB
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Re: Control gyro gain with throttle trim

Post by MikeB » Thu Mar 26, 2015 12:23 pm

Yes to the range of 0 to 100%.
Each 'click' of the trim will change the output by 0.8%. This does correspond to the step size you get with a trim increment of 1 when going from -100% to +100%.

So, yes, you will get the equivalent of a step size of 1.

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Re: Control gyro gain with throttle trim

Post by MikeB » Thu Mar 26, 2015 3:09 pm

I have one method implemented so that if a trim is being used as the source of a GVAR, then the trim increment for that trim is forced to be exFine.
I still not quite sure whether this is a good idea, or if making a trim switch able to increment and decrement a GVAR directly would actually provide the same effect and be better.

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jhsa
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Re: Control gyro gain with throttle trim

Post by jhsa » Thu Mar 26, 2015 3:38 pm

That would for sure work well with ersky9x and the new implementation of the adjusters. It would be great if this could also be implemented the same in er9x ;) That would solve the problem and no workarounds would be needed?

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willhac
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Re: Control gyro gain with throttle trim

Post by willhac » Thu Mar 26, 2015 5:27 pm

The mix works as expected with output steps of 0.8, perfect ! :D
Only in eepe : in mode 1 it seems that Ttm follows left vertical trim instead of throttle trim (I had to use Etm as source of GVAR)

What about having the options : OFF/exfine/fine/medium for Tr. trim instead of ON/OFF ?
The direct control of a GVAR with the trim switch would be great too... Perhaps this function could also be used with the additionnal push buttons in the future ? João's idea of 2 buttons on the back of the radio is very good.

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